As the calendar turns to September, all 30 MLB teams can call up their top prospects to get a look at them for the last month of the season. This annual ritual has often provided teams with the opportunity to evaluate young players, rest veterans and muddy the playoff picture. Many baseball pundits claim that it is not fair to play all season with 25 guys on the roster and then allow teams to expand to 40 players for the last month as new bullpen arms are added and new pinch hitters are now available. Of course, each team has this same opportunity, so it is fair in that respect. But we often see teams filled with Triple-A players playing against teams of Major Leaguers, creating a bit of a competitive problem as we try to paint the playoff picture. So how does this affect your fantasy baseball race?

You now have to evaluate pitching matchups a little more closely. You have to consider if your starter will go on a particular day or if he was backed up a day in favor of a youngster getting a look. Teams out of contention might go to six-man rotations or possibly shut down a young pitcher who has built up a lot of innings. Pitchers may be skipped or innings limited to preserve them for October or maybe future years of their career. All of these can affect your win total as you may end up facing a different opponent or starting pitcher than you expected. Its not good to find that your pitcher was bumped back a day and will miss an opportunity at improving your WHIP and ERA against the light-hitting Oakland A’s, compared to facing the 2009 edition of the Bronx Bombers.

Teams in playoff contention might rest star players so they aren’t so worn down for the playoffs. Since the St. Louis Cardinals are so far ahead of the competition, they may rest Albert Pujols and Matt Holliday an extra day each week in preparation for the playoffs.

Meanwhile, Chipper Jones will likely play every day he can to keep the Atlanta Braves playoff hopes alive. With these facts in mind, you’ll see the Cardinals trying but not at all costs. You’ll see the Braves fighting for their lives and pulling out all the stops to win. You’ll also notice the Washington Nationals playing like they have nothing to lose (because they don’t) and anything they can do to impress the Washington top brass could mean a chance at a roster spot next spring.

All this is a lot to keep in mind when making roster decisions. It’s always best to go with your best hitter at each position, but pitching matchups are tricky. Pay close attention to how the teams your pitchers play for are using their rotations and when in doubt, go with the best pitcher on your roster.