Sunday was an incredible day for Chicago Sports! The Bears came back from a 23-6 4th-Quarter deficit to beat the Lions. The White Sox beat the Tigers 5-2, making it their 8th win in nine games. And finally, to top it all off, Alec Mills threw a no-hitter in the Cubs 12-0 victory over the Brewers in Milwaukee. If you told me a Cub was going to throw a no-hitter this season, my money would be on Yu Darvish. Alec Mills seemed like an unlikely candidate.
The typical no-hitter candidate is someone who strikes out a very high number of batters. This is because each out recorded by a strikeout is an automatic out. It’s one less batted ball put into play. Batted balls can be weird, there’s an element of randomness associated with them: fielder’s positions, fielder’s abilities, the ballpark and the weather can all affect whether a ball in play is a hit or not.
Alec Mills is does not fit that typical no-hit mold. Out of the 44 qualified MLB starting pitchers, Mills ranks 39th in strikeouts per 9 innings. Part of his game is that he pitches to a lot of contact. That did help him on Sunday in one area as he was able to keep his pitch count down low enough for him to complete the game.
In Sunday’s no-hitter, Mills only struck out five batters. With 27 outs in a game, that leaves 22 outs to be recorded by balls in play. Mills recorded those 22 outs on 21 balls in play (one double play). Below, we look at Statcast’s expected batting average of each of those balls in play. (Expected batting average uses the exit velocity and launch angle of those balls to determine the average batting average on similarly struck balls from previous games).

The last column shows each batted ball’s expected batting average. Jedd Gyorko had one with a .810 expect batting average, Yelich had one with .740 and Arcia one with .610! Obviously these all ended up outs, but the average expected batting average on these balls in play was .302! The Brewers were expected to hit over .300 on these balls and they didn’t get a single hit. That’s incredible! 11 of the 21 balls in play were “Hard-Hit” balls too (Over 95+ mph exit velocity)!
For comparison, let’s look at the other no-hitter thrown this year (Lucas Giolito).

There’s some really important metrics here. The red highlights “Hard-Hit” balls. We see that Giolito only allowed two the entire game, while Alec Mills allowed 11. Next we see that Mills also had seven more balls in play than Giolito; creating even more potential randomness.
By using the expected batting average we can calculate the probability of none of these batted balls becoming hits (a no-hitter) given that strikeouts have a 0% chance of becoming hits. What we find summarizes how unlikely Mills’ no-hitter really was.
Lucas Giolito’s probability of throwing a no-hitter August 25th = 0.34%
Alec Mills’ probability of throwing a no-hitter on Sunday = 0.01%
I’m curious if any no-hitter has ever had that low of a probability! I doubt it, but we’ll never know since we haven’t had statcast data for very long. Yes, the Cubs must’ve done a great job scouting and with defensive positioning, but you have to have some luck too.
Given that we don’t have all that data, I can’t say for sure this was the most unlikely no hitter ever, but you would be hard-pressed to find another one like it. And piggy-back that off scoring four runs in the 9th off Josh Hader to win 4-2 the night before, add in a 23-6 4th-quarter comeback by the Chicago Bears on Sunday and that has to be the most improbably good sports weekend for Chicago fans! These kinds of games are what makes sports so amazing.