Ah, deep leagues. They test your knowledge and patience, your ability to follow a draft strategy and your sanity, as injuries always tend to ebb away at the weakest spot of your rosters. As 18- and 20-team leagues continue to become more popular, it's worth looking at some unique strategies that don't apply to shallower leagues, but can give you a decided advantage when you're in a league that goes 500-800 players deep.

I'm lucky/stupid enough to participate in several uber-deep leagues of both the redraft and keeper variety, and the more I play in said leagues, the more I grow to appreciate them over their shallower counterparts. The deeper the rosters go the more knowledge is required to succeed and the more victory has to do with skill and not luck.

With that in mind, here are two lessons that have really been hammered home for me as I've completed several deep league drafts this season.

1) Prospects are overvalued; post-prospects are undervalued
My fantasy boss/internet father Bret Sayre often makes the point that the deeper the league you play in, the more valuable replacement-level fantasy players become. The reasoning behind this is pretty simple: if you have to replace Matt Kemp in a 12-team league, you're going to get a decent replacement along the Norichika Aoki/Josh Reddick line. If you need to replace Kemp in a 20-teamer, I hope I can interest you in some David Lough!

This emphasis on adequacy means that selecting prospects is an even riskier proposition in deep leagues than in leagues of a standard size. Sure, the allure of a George Springer or a Gregory Polanco is very real, but what if neither player receives more than 250 PA this season? You might want to pop Javier Baez in the fifth round of a deep league, but if he's in the minors until July you're putting a serious dent in your ability to compete this season.

In dynasty leagues the picture gets even more muddled, but if we stick to evaluating redraft leagues here, you should be valuing boring production (think Michael Brantley) over high-upside, high-risk propositions (think Jake Marisnick). There's a fair counterargument to be made that landing this year's version of Yasiel Puig in the 20th round could win you your league, but players like 2013 Puig don't come around very often.

One strategy you can take to land younger players in deeper leagues is to target post-prospects with a good chance of getting a second chance in 2014 rather than spring for more promising minor-leaguers who might not see much MLB time. For example, consider taking Trevor Bauer (aggregate ADP of 474, courtesy of a few rounds later than someone else pops Noah Syndergaard (aggregate ADP 331). This works for hitters, too: you can take Mike Olt (443) much later than Kris Bryant (365).

You're not going to get many oohs and ahhs in the draft room for taking guys like Bauer or Olt, but they have just as good a shot as impacting your 2014 team as do sexier prospects who've yet to expose their flaws to the world, and you can target these players much later.

2) Outfield is really, really thin
The staff collectively addressed this a bit when we went over all of our outfield rankings this preseason, but it bears repeating here: outfield is much thinner than you think. In shallower 10-to-12-team leagues, you can get by with one or two big names and then guys you personally identify as sleepers later. But in leagues with 16 or more teams, good luck.

Allow me to be captain obvious for a moment: in 20-team leagues with five outfield starters, you're going to see around 160-180 outfielders selected. Do you know who the 100th-best outfielder by aggregate ADP is? It's Garrett Jones. Sitting at 120 is David DeJesus, and after that the ADP aggregators pretty much give up. It's fine to select a Cody Ross or a Matt Joyce or a Nate McLouth with the expectation that that player will give you some counting stats off of the bench. But if you're counting on that ilk of player to start, you're in trouble, even in really deep leagues.

To whit: In the TDGX league (20 teams, five starting OF, standard 5×5, dynasty), I ended up with an outfield of Hunter Pence (round.overall: 3.55), Oswaldo Arcia (7.135), Curtis Granderson (8.146), Ben Revere (13.255), and Josh Willingham (17.335), with Carlos Quentin, Jon Jay, and Logan Schafer all on my squad, too. The context is a bit different here since this is a dynasty league, but nonetheless I think I clearly prioritized outfield over some other positions as my draft went on, including occupying my two primary UT spots with outfielders in Quentin and Jay. (And if you’re looking at that outfield and thinking it's a sorry bunch, you should see some of the other collections of outfield "talent" in the league.)

What this tells me is that in deeper leagues I really need to make sure that at least three of my outfielders are reasonable, no-doubt starters and that at least three of my utility/bench spots need to go to outfield-eligible players, roster permitting. This means you might need to condition yourself away from viewing outfield as a lesser position on the positional value scale, particularly in the earlier rounds.

If you have any strategies you've tailored specifically to deep leagues, feel free to leave them below and perhaps I'll parse them out in a column in the future. Deep leagues are a really interesting format that I think is just starting to gain mainstream fantasy coverage, and the need to refine and eventually to adjust these strategies is something that truly appeals to me.