At 47-43, the Pirates are just 10 games short of last year’s win total even though they’ve played just 56% of the season. To match last year’s disaster, they’d have to go 10-62. To lose 100 games, they have to go 15-57.
With 72 games left, the Pirates need 35 wins to finish above .500 for the first time since 1992. This means they’re not home yet: anything worse than a 35-37 record will put them at .500 or worse. There are good teams that will have records worse than this in the second half.
In the last five years, the NL Central Champions have won: 91, 91, 97, 85, and 83 games. That’s an average of 89.4 wins; to reach 89 wins the Pirates will need to go 42-30 in the second half. To reach 91, the total it’s taken to the win the division the last two seasons, they need to go 44-28. This seems like a rather long shot to me; the best way for the Pirates to stay in contention is probably for no one else in the division to pull away.
In the last five years, the NL wild cards have won: 91, 92, 90, 90, and 88 games.
Prediction: the NL Central is not quite as bad as people currently think. It will take at least 87 games to win the division.
Prediction: the Atlanta Braves are not quite as good as people currently think. It will take no more than 93 wins to win the wild card.
Therefore: it will take the Pirates between 88 wins (41-31) and 93 wins (46-26) to make the playoffs.
Begin theoretical analysis.
The Pirates have, by my count, 30 games left against the Cubs, Astros, Marlins, Dodgers, and Padres. The Marlins are currently the best team of ths group at 43-48. IF the Pirates win 20 games against these teams, they will need to go 21-21 against the rest of their schedule to reach 88 wins, which is mostly comprised of the Brewers, Cardinals, and Reds with 13 games (3 apiece except for four vs. Atlanta) against the Phillies, Braves, Giants, and Diamondbacks.
Conclusion: It’s still improbable that the Pirates make the playoffs in 2011, but it is neither impossible nor even implausible. Their easiest route to the playoffs is to continue beating the bad teams on their schedule, and make sure to split evenly against the rest of the NL Central. If they go 14-15 against the Cardinals, Reds, and Brewers, but most of those losses come to one team (ie, the Brewers), they will probably lose the division.
Disclaimer: My math looks good to me, but it might be slightly off.