The Twins spanked the Indians this afternoon 11-3, collecting four home runs on thirteen hits. Three of the singles came off the bat of Joe Mauer. His 3 for 4 day raises his batting average to .436. Given Mauer’s general abilities, we should start considering the chance that he hits .400. Here’s a graph showing the probability by game day (click for a larger image):

Joe Mauer probability of hitting .400, through games of June 4, 2009

I’ve included graphs of two probabilities. The 162 line looks at his total at bats based on a 162 game schedule. That assumes he gets injured at the same rate all year. The 140 line assumes he started the season fresh at game 23, with the original injury having nothing to do with his injury rate for the rest of the season. The 162 line predicts a lower number of at bats for the season, so a higher probability of Mauer hitting .400. I’m using .317 as his career batting average, as that was his mark entering the season.

As you can see, the odds are actually pretty good for him using either line. The 162 graph puts him at 0.024 or about 1 in 40. The 140 graph’s current value is .0023, about 10 times lower. Still, a 1 in 440 chance isn’t bad, considering how tough it is to hit .400. It will be fun to see where the two graphs start converging.