Who Were the Luckiest and Unluckiest Starting Pitchers in April?

The MLB regular season is a marathon, not a sprint. That’s why we shouldn’t jump to conclusions when a player gets off to a slow start in the month of April -- after all, it doesn’t mean the next five months will also be terrible.

Just take Anthony Rendon as an example -- before Sunday’s game against the New York Mets, he had struggled to a 59 wRC+. But after his 6-hit, 3-homer and 10-RBI performance, his wRC+ for the season was a healthy 107.

So, one way or the other, things can turn around pretty quickly on the diamond, especially when certain statistics haven’t stabilized yet.

While we should take fast and slow starts with a grain of salt at this point, it’s important to look at certain trends to see how players arrived at those numbers. Did they really earn that stat line, or was there more luck involved than usual?

That’s what we’re here to figure out each month -- which players experienced more bad luck than the average, and who ended up on the other end of the spectrum.

On the pitcher’s mound, the most common statistics we see thrown around include win-loss record, ERA and WHIP, but we all know there’s more to individual performances than that.

So, when looking at how lucky and unlucky certain pitchers were over the past month, we’re going to compare their ERA to their Skill-Interactive ERA (SIERA).

According to FanGraphs, SIERA attempts to measure the underlying skill of a hurler. Unlike FIP and xFIP, SIERA doesn't ignore balls put in play, and it also attempts to give a more accurate picture as to why certain pitchers are better than others. A good SIERA is just like a good ERA -- the lower the better.

For this exercise, we’ll be looking at starting pitchers who have finished April qualified for the ERA title, which spans 104 hurlers.