ESPN has published its mid-May fantasy baseball rankings. It is an average of the individual rankings of their various experts and so represents a kind of generic zeitgeist on who’s good and who’s not. What is missing is the context of the game being played.

After the top 50 players or so — the ones desired in any format in any matchup — the game being played makes all the difference. Here are three examples that focus on hitting. I’ll write about pitching in another post.

First, player strengths in head-to-head formats are different than in rotisserie formats. When stats zero out every week against a new opponent, batting average or OBP are far less important than runs, home runs, RBIs and steals (see my Wins by Category analysis). Hitters must have power or speed or both to make a significant difference in head-to-head.

Second, roster depth matters. If a league offers deep enough rosters for a manager to platoon, David Ortiz, for one, is much more attractive. Even as his terrible April has turned into a very good May, he is most potent and most likely to get at bats against right handed pitchers. A platoon of Ortiz and any comparable hitter will give you just as much value as a single slugger ranked twice as high — one, it is important to remember, that you would not be platooning.

Finally, the rankings are based on projected player performance for the rest of the season. This is the nature of the exercise. The results tell you who to own, not who to play. But most leagues allow a substantial number of transactions, making who to play right now a decisive question. If you can play a great player for a month, then get an adequate substitute off the waiver wire, you need to do it.

This is the case among catchers. There are a handful of great hitting catchers and all the rest are interchangeable. So it is bizarre to see Mike Napoli ranked so low. Since starting catcher Jeff Mathis went on the DL, Napoli has not only hit extremely well, with a 1.106 OPS in May, but has played almost every day. Angels Manager Mike Sciosa went from hating the guy to running him into the ground, and Napoli has done nothing but hit. The rub against Napoli is that he will get bumped into a backup roll again with Mathis’ return. This may be true. But it shouldn’t obfuscate the fact that at this given moment Napoli is one of the top fantasy catchers in the game. He’s up there with Joe Mauer. In head-to-head leagues where batting average or OBP is less important (see above) he is, quite simply, the best.