I took the regular season stats from last season, identified each pitcher with his role (starter/reliever) and his arm (righty/lefty), then tabulated the results. The basic findings:
- Righties pitch 80% of innings.
- Righties start 80% of games.
- Starters pitch 73% of innings.
- The average start lasts 6.35 innings.
- The average relief appearance lasts 1.45 innings.
The surprise to me was that, apart from the fact that they’re used in different amounts, righties and lefties are used very similarly. Lefty starters stay in the game as long as righties. (A bit longer in fact!)
The biggest difference seems to be that the average relief outing is longer for righties, 1.48 innings vs. 1.33 for lefties. That’s the LOOGY factor, but I thought the difference would be even greater.
The totals are shown below, grouped into a few different comparison pairs.