You're probably correct if you believe you need to 12 pitchers to keep your ERA down. At this point, your the two major options I'd consider are:
- Go with 11 pitchers, 14 batters and set your team have a long Hook for starters and relievers. Considering this is the modern day setting, your ERA will probably go up. You might consider placing higher value on high-stamina pitchers. You might want to see if the rest of the league's ERA is going up. It doesn't really matter if your team ERA goes up 0.50 if everyone else in the league is going up 0.50 too.
- Go with 12 pitchers and 11 batters. You'd need to make sure that you put defensive versatility at the top - I imagine that the AI might not know to do this. You'd need a backup catcher that can also spot at the corner IF or OF positions - you can't afford to have a guy sitting on the bench with only one purpose, infielder capable of playing all four positions, outfielder that can play CF well. If you need a DH, that's going to be a little rough. Of course in a non-DH league, you're going to have the issue of pinch hitting for your pitchers.
Between the two, I'd probably opt for #1. How is the AI dealing with it? Are they running out 10-11 man staffs now?