It’s finally here. Real baseball. Major League Baseball. Baseball that counts. Baseball that we can count. And so, naturally we begin to think about great Opening Day performances. In 2013, Bryce Harper delighted the baseball universe by hitting not one, but two home runs. Yes, Opening Day is arbitrary and it would be just as important in the long run if Harper hit 2 home runs on June 15, but Opening Day is the baseball fan’s Christmas morning. Everything seems to mean a little more. And those home runs seemed to mean a great deal.

As impressive as that performance was, Harper would have had to hit a couple more to equal the greatest Opening Day performance in history. I wanted to know who should get that credit. So I did my best Sam Miller impersonation and fired up Baseball Reference’s Play Index Game Finder. I’ll be using Win Probability Added (WPA) as a way of measuring great performances. As a reminder, WPA measures a player’s performance as a function of percentage change of his team winning added or subtracted based on his actions (hitting and pitching only). For that April 1, 2013 game, Harper’s WPA is 0.198. That means he made his team 20% more likely to win than they otherwise would have been. That’s a good day at the office, but nowhere close to the all-time Opening Day leader.

Because they are credited for every play when they pitch (including great defensive plays) and WPA is a cumulative stat, it is almost always going to be the case in a search like this that the leader is going to be a pitcher rather than a hitter. That is true in this case. The leader for best WPA by a hitter on Opening Day is Raul Mondesi for the Dodgers in 1999 with this line:

As you can see, Mondesi duplicated Harper’s 2 HR but has a MUCH higher WPA. This is due to the 6 RBI (Harper had only 2) and the 2 singles. Mondesi had a great day, increasing the Dodgers’ chances of winning by 106% all by himself.

But, as we said above, the greatest single WPA is most likely going to belong to a pitcher. And that is the case here. The distinction of greatest Opening Day WPA belongs to Cleveland Indians hurler Mel Harder, who on April 16, 1935 scored a WPA of 1.454 against the St. Louis Browns. That’s right, he made the Indians 145% more likely to win in that day. For context, this FanGraphs intro to WPA as a stat indicates that a cumulative WPA of 1 (in the modern era) for an entire season makes one an average player. Harder outdid that in one day. How, you ask? He threw 14 innings, giving up only 1 run and earning the win.  Talk about getting stretched out at the beginning of the season!

One feels bad for his opposite number on the Browns, Bobo Newsom who did almost exactly the same thing but gave up one more run and took the definition of hard-luck loss.

Look at those numbers! The same number of walks and strikeouts of each pitcher. The same number of innings pitched, 53 versus 56 batters faced. And Bobo Newsom went home that night with a loss on his record.

What is to come on 2017 Opening Day(s)? Only time will tell. Pitches will be thrown, home runs will be crushed, bats will be flipped (one can hope). But there is one thing I’d be willing to bet the farm on…. Buck Showalter will not leave Kevin Gausman out there for 14 innings. Happy Baseball Christmas!