Keep track of the available arms with the bullpen usage chart.
At the end of the post you will find the link to the PDF containing all the match-ups of Sept. 13. The charts show the number of pitches thrown by each team’s pitchers each of the last seven days.
How to read them:
Above the thick line in each chart you see the starters, sorted by their WAR; below the thick line are the relievers, again best to worst according to WAR. Darkest colored cells indicate highest workloads. The probable starting pitchers are listed at the bottom of each chart.
You can read about the bullpen usage chart in this introductory article.
Bullpen usage chart – Sept. 13 (PDF ~ 400K)