A growing and ever-more popular format to fantasy baseball leagues is the dynasty format. The “dynasty” term is one that is thrown around quite freely among a lot of fantasy baseball players so we will be sure to separate keeper and dynasty leagues for the purposes of this strategy primer as well as give you the key pros and cons to the formats and why in the long run it will actually make you a smarter, and more involved baseball fan in reality and grow your understanding of what teams are looking for in trades and signings.
Definitions
First things first, we have to clear a few things up to get on the same page. A “dynasty” league, like the title the piece references, is one in which you can keep players for however long you want and there is typically zero penalty or additional price assessed for you to keep those players. A “keeper” league is one in which managers can keep players for certain lengths of time with either zero or some additional penalty/price for doing so. Both can have identical formats and be either mixed, AL, or NL-only formats, and involve prospects or international players. The real difference is determined by length of time a player can remain on your roster and that certainly changes the strategies involved.
Roster Construction
In both formats, building out your rosters is essentially the same, however, as we’ll explain, there are differences to consider with who to carry from year-to-year. If you are just starting out in a brand new league, all rosters are clearly empty and thus the draft will fill out everyone’s roster the same way whether it be by snake draft, auction, third-round reversal, random number generated rounds, or what have you. So clearly this section is really more for clarifying the additional years of these leagues.
Keepers: If you’re in a keeper league, you’ll have some choices to make based on hard counts of how many players you can carry over and the best way of determining who to keep is the players that will bring back the most value. Value is a tricky term to use because everyone views it differently as it could mean shear return on investment, AKA you can keep them for a tenth round pick and they’re going in the fourth round currently or they’re valued at $20 and you can keep them for $10. Or it could mean they are valued because of the strategies they open up to you during your draft because they are a multi-positional player or fill hard-to-get categories. Trying to go into the draft with the best combination of players and already gained value is how you dominate keeper leagues for the long run. The other thing to keep in mind with this format, that doesn’t necessarily apply to dynasties, is how close a player is to their peak because obviously if you only get them for a few years, you’re trying to maximize the exposure to the peak. If your league caps the number of prospects you can have you’re also trying to keep the best possible ones in combination with those that may help your team sooner rather than later.
Dynasty: Dynasty leagues don’t have time limits on keeping players and they also don’t have increasing penalties for holding a player year after year so in terms of value it’s really just about keeping the best players that can help you win and for the mid-or-lower-tier players it comes down to who you think, or know, will be available come draft day to fill those roster spots. Injuries and trying to maximize peak years also weigh less in these formats because it’s not necessarily wasted value if a guy only gives you a part of a campaign due to injury or doesn’t live up to the projected value you thought he’d have. You still want your team to do as best as possible clearly, but if it doesn’t cost you anything to hold a player, paying $10 for a presumed $20 player who only turns out to be worth $5 isn’t the worst thing in the world. For prospects in this one, this is where the in-depth knowledge and planning really come into play since you don’t want the prospect to be blocked when they’re ready to contribute and you also don’t want to invest a few seasons carrying what you thought would be a top prospect and then have them not really do anything for their major league club. So while the keeper format is more about what can I get from this player sooner rather than later, dynasty is a great combination of needing the best players now but also having their replacements ready when they start to waiver.
For both leagues once carry over players are decided it really comes down to filling out your rosters with the remaining players in the draft for however your league does it. Personally, auctions are the most strategic and fair way to do either of these leagues but to each their own. When drafting, the same logic talked about above in terms of deciding on which players to keep or take applies for each separate format. Keeper leagues you’re looking to maximize the value of the players you’re taking right off the bat and trying to focus on the players in the primes of their careers or close to it on either side, while in dynasty leagues you’re focusing on getting the youngest, best core group of players possible so they can stick together for several seasons and keep you in contention as long as possible.
Draft Strategies
While both formats are made of long-term plays for players, there are different intricacies about drafting players and when and what gets the focus at different points of the draft. This is perhaps the most important couple of formats to be looking at a player’s three-year trends or averages in preparation for the draft as well as knowing how to utilize, at least basic, sabermetric or advanced stats because they tend to hold truer over a few seasons than they will for one-year samples like you focus on for redrafts or even draft and holds. Outside of the nuances mentioned below, drafting in these leagues can be thought about much like the single-year formats mentioned above. Let’s break down some of the differences between keeper and dynasty leagues though.
Keepers: The first thing that comes to mind is the importance of knowing who’s coming back from injuries or who the more injury-prone players are since you may only have the player for a year, depending on keeper value the following season, but at most you only have them for a few years and you don’t want to waste them on an injury-risk of a player. It doesn’t really matter the position for this advice either. The second thing to keep in mind that is 
perhaps a bit different from true dynasty formats, is that position scarcity will still matter in these drafts, though not as much as it will in redrafts. The reasoning is that you are only getting these players for a max of a few years and with the typical development time for prospects, the immediate shortcomings at some positions won’t be fixed that fast. Take for instance the catcher position. There are only a few top catchers to work from currently with the others being no better than average. While I have 22 catchers listed in my Top-250 prospect rankings, they are all at various states of development, not to mention that catchers typically take longer to develop, so they aren’t coming and making a splash a year from now to give you immediate help. So keeping in mind position scarcity and then capitalizing on filling those holes with up-and-coming prospects in those spots is really how to sustain your success for a long time in keeper leagues. A tiebreaker in keeper leagues when drafting players, should be the future value of each player. If you have both players ranked very similarly, look at what you can draft both in terms of round or auction value and what the prospective lineup or rotation around them will look like over the next few years. For example, let’s say you’re between Gleyber Torres and Javier Báez this year, both players going within four or five picks of each other and similarly priced auctionwise. If you’re appropriately taking things into account for keeper formats, the pick would be Torres because for the next few years he’ll have the better lineup around him and the Yankees farm system is far deeper than Chicago’s so even if New York needs help, they can pull it from their own stockpile rather than having to sign or trade for players like Chicago.
Dynasty: While injuries should play a role in your thinking when selecting players to keep or draft, it’s not as serious of a thing because you have basically the rest of the player’s career to hold them and so losing a year out of ten isn’t as bad as losing a year out of three like you would in a keeper league situation. There have been a few mentions of “peak” years already and for each position that’s really different but generally for a hitter their power peak starts at age 27 and goes through 30-31-32 generally. However, that doesn’t mean that they aren’t still valuable before that as we’ve seen countless prospects come up and absolutely take off from the jump with an even higher ceiling coming in their peak years. This is where the main difference is for dynasty as getting guys that are just coming up is the best strategy for long-term success because you maximize the valuable years they are rostered for not just trying to get the best two-to-four-year stretch out of them. This is also why sabermetrics and analytics are best utilized for dynasty leagues.
Switching to the position scarcity topic, it’s actually a bit of reverse thinking of sorts in dynasty leagues with position scarcity. Everyone is playing with 
the same short-handed positions in the majors, and the same development time to fill those positions with depth. Thus, everyone is trying to get a bevy of prospects that will pan out and be productive in the majors, but in the minors, the position scarcity continues in terms of top prospects and certain positions. There are 22 catchers in my Top-250 prospects right now, but there are just nine second baseman and ten first baseman. So making sure to grab prospects in short positions is a slightly bigger focus in dynasty formats to set yourself up for long-term success year-after-year. Another more niche thing to consider in dynasty is players that are settled in with a team either because of role, contract, or both. There are numerous players, mostly utility infielders and pitchers, that are seemingly on a different team each season or every other season at this point and for dynasty leagues that can create an issue with appropriately trying to figure out their projections, or role, or value from year-to-year as their home park, division, opponents, teammates, and coaching staff would all be changing and considering baseball players are creatures of habit who perform better the more consistent their surroundings are, guys that move a lot may hamper your efforts in a dynasty league.
Pros and Cons
The pros to both formats are that as a manager in these leagues you will gain a deeper understanding of the game and a fondness for following teams outside of your normal orbit. Though there are some individual pros and cons to each format. One general con for both is that they are much more involved strategically than standard single-season leagues and it gets more so if you’re in AL or NL-Only formats.
Keeper: In keeper leagues we’re still getting the benefit of knowing what’s coming in the pipeline for major league clubs and that can really pique baseball fans interest even more, especially if it’s a prospect for your favorite team that you’ll invest in watching the development of. Another benefit of this format is that while it’s looking longer down the road than redraft leagues, it’s not as far reaching as the dynasty format and so those that only want to try and sort things out over the next few seasons, keeper leagues afford them that opportunity. The main con with this format is that you may have spent a few years keeping a player or holding them since they’ve been a prospect and then you’ll have to throw them back into the pool just when they reach their peak values.
Dynasty: The main pros for dynasty formats are that for those of us who wish they could be an actual MLB GM, this is as close as we’ll get, sans MLB The Show on PS5. It also gives you the feeling of managing a minor league system and trying to make trades that have seasons-worth of implications on both team’s rosters. The other main pro, over keeper leagues, is that you can hold a player all the way through until you decide you no longer want them. So if you’ve had a player since they were a young prospect and now they’ve come up and hit their peak, there’s nothing making you get rid of that player, aside from your own feelings about them. The biggest con with this format is that it takes a lot of time to be good at these leagues and you have to be on top of what’s happening at all levels of pro ball to really maximize your roster. You can also wind up with players who are dead weight on your roster, either active, minor league, or bench because they had a bad season and you get caught for another season holding them hoping they turn it around because you are less likely to cut players as quickly if there’s no restriction on how long you can roster them for.
Overall Thoughts
Generally these leagues are the best that fantasy baseball has to offer because of the depth of play they require and the knowledge of the game you’ll gain as a fantasy manager. Knowing that a team trading player X has repercussions for player Y on the other team will make you an overall better baseball fan and enjoy the nuances of the game more. Anyone can play a one-season league and have a solid draft and then hit the waiver wire or FAAB jackpot and pick up the must-have hitter or pitcher and get a championship that year. And congrats to them because it’s still hard to win a baseball title, however keeper and dynasty league titles are more satisfying because it can take a few season’s worth of moves and correct decisions to ultimately get you the lineup that wins the title. If you want leagues in which developing players over a few years and having to make strategic roster decisions that can affect things a year or two down the road, keeper and dynasty leagues are the formats for you.