Statistical regression is a fact of life in Major League Baseball.
Many times, when a player performs at a level well beyond personal bests or even league bests, you can expect to see their numbers decline over the next season (or whatever period of time you want to use to analyze the situation).
When it comes to the Cubs’ Jake Arrieta, who is coming off of the greatest second half in the history of the game, regression was unavoidable. As much as fans would have loved to see Arrieta continue to hold a sub-1.00 ERA for the long-term, the fact of the matter is that doing so is a near statistical impossibility.
Not enough can be said about how utterly dominant Arrieta was in 2015, specifically in the second half.
In the second half last season, Arrieta posted a .75 ERA, an opponent on-base percentage of .204 and a BABIP of .207, allowing just two home runs during the same time period. In layman’s terms, he was historically great.
While these second half numbers were incredible, he was certainly no scrub in the first half of 2015. Arrieta posted a WHIP of .865 last season, allowing the fewest hits per nine innings (5.4) in the league, while also striking out 236 batters over 229 innings pitched.
With all of these numbers in mind (and there are still plenty of others which indicate just how dominant he was), it’s easy to see why he won the NL Cy Young.
Of course, these numbers were frankly unsustainable entering this season and going forward. Most rational fans recognize that maintaining a sub-1.00 ERA like Arrieta’s is unthinkable to even consider.
In fact, it’s somewhat ridiculous he maintained one for as long as he did. Anyone who watches the Cubs on a daily basis and sees every Arrieta appearance can recognize that he isn’t the same unhittable beast that he was in the latter half of 2015.
That doesn’t mean he’s not still pitching incredibly well, however.
When compared to last season, his FIP is slightly higher, going from 2.35 overall in 2015 to 2.57 thus far this season. His BB/9 is also up this year, a full walk higher than last season in fact, which has subsequently raised his WHIP as well (although it is still below 1.00).
With these numbers in mind, it’s important to see that he has some numbers which are actually better this year than the ones he put up last season. His HR/9 of .31 is lower than last season’s .39, which led the majors. His K/9 has also increased slightly this season.
In terms of Wins Above Replacement, Arrieta is currently sixth in the majors among pitchers, fifth in the NL, in fWAR, coming in at 2.6 so far in 2016. Needless to say, if you are in the top six across all 30 teams in terms of WAR, you’re doing something right.
It’s obvious that Arrieta is not dismantling opposing offenses like he did from July-onward last season. That said, he is still one of the best pitchers in the major leagues and the numbers back that up. It’s still early but it’s obvious that he’s not the favorite to win the NL Cy Young Award this season, because Clayton Kershaw is having his own historic run this year. Nonetheless, Arrieta is still the ace of this Cubs pitching staff and is one of the best starters in baseball again this year.
So what does this all mean?
It means that Arrieta deserves an immense amount of appreciation from fans around baseball, whether it’s from supporters of the Cubs or any other team, from casuals and hardcore fans alike.
The fact that he is going through regression and is still one of the elite pitchers in baseball demonstrates just how good he is. Even if his numbers are slightly down in some cases, Arrieta is still pitching at a nearly-incomparable level, a fact which continues to deserve colossal amounts of praise.