January is absolutely flying by, and we’re rapidly approaching draft season. If you don’t already have your leagues locked down, you’ll be doing so shortly. Tout Wars and LABR both set their league rosters this past week—of note to BP readers, I’ll be leaving Tout Wars NL and moving back to Mixed due to the Astros-related roster contraction while Jason Collette will be moving from LABR AL to Mixed, where he’ll team up with Paul Sporer. This expert league movement reminded me of a request I received from reader Robotey back in August that I was waiting until the preseason to address:

@Derek — I don't know if this under your purview, but as Fantasy devotees go I am strongly of the school that deep 'only' leagues are the only ones worth considering–precisely because they can lead to these tests of attrition that I am currently undergoing. Any chance you may feel similarly may write a passion piece about the test of humanity that is the 'deeper league'?

While I won’t go as far as to say that “deep 'only' leagues are the only ones worth considering,” I do vastly prefer “only” leagues to mixed leagues. So, for those of you still debating what kind of league (or leagues) to play in for the 2013 fantasy baseball season, here is my attempt at persuading you to give an AL- or NL-only league a shot.

While mixed leagues have the built-in fun factor of getting to own multiple superstars, I find it much more gratifying to draft the lesser-known players who outperform their market-based expectations. Mixed leagues often become a game of stars and scrubs, ultimately being decided by whomever’s stars stay healthy and whoever’s scrubs break out. They disproportionately shift in the direction of whoever manages to make the best April pickups. In the first month of the season, tons of players outperform expectations due to nothing more than small sample sizes and luck, and often you’re merely rolling the dice on one or two of these guys in the hopes that you manage to get the one who proves to be legitimate. Whoever lucks into Jose Bautista has a huge advantage. Yes, whoever drafts Bautista in an AL-only league has an advantage as well, but in a deep league, nearly every player of note gets nominated on auction day. You’re put to a decision on every player on day one. This adds an element of skill that is absent in the piñata-candy-snatching frenzy that is a mixed-league April.

AL- and NL-only leagues force you to play close attention to everybody. In a mixed league, Cleveland’s backup catcher can safely be ignored, but in an AL-only league, Lou Marson has value. In a deep league, you’re not just caring about prospects like Mike Trout and Bryce Harper; when the Twins recall Brian Dozier to play every day at shortstop, you have to be all over it. It’s easy to say that Adrian Beltre is good; it’s much harder to put a price tag on Kyle Seager. Playing time situations have to be watched closely. A big chunk of guys on mixed-league rosters are locked into playing time, but in deep leagues, you have to decide what to do with a floundering James Loney; is he going to pick himself back up, is he going to be benched, is he going to be traded? Don’t think you’re just going to drop him; yeah, he’s James Loney, but that’s still better than Brooks Conrad.

AL- and NL-only leagues also open up new avenues for strategic thinking. How do you want to structure your roster? If you’re not careful, you’ll end up with holes (or worse, Wilson Valdez) in your starting lineup… unless you’re okay with that and decide to make up for it elsewhere. Would you rather draft a so-so asset who will contribute immediately or gamble on a prospect that might not make it to the majors until July? How do you want to spend your FAAB? Does this decision play into how you structure your roster and spend your money on draft day? Do you want to spend here and there on the Doziers of the world or save up in the hopes that Zack Greinke gets traded over to the American League? In mixed leagues, FAAB bidding is far less exciting and even less challenging. The only guys worth going after are guys in the midst of a potential breakout, newly anointed closers, and the few top prospects that are recalled into regular playing time that aren’t already owned.

Of course, this is all mere opinion—there’s no right or wrong answer here—and there are certainly drawbacks to AL-/NL-only leagues; if one of your big-ticket items gets injured, that might be all it takes to cost you the league since solid replacements are so hard to come by. For me, however, I far prefer the challenges and the ultimate gratification of deep leagues. Where do you guys stand?