The myth of Craig Kimbrel's decline

The Red Sox traded for Craig Kimbrel over the weekend and — I know this will shock you — the internet had some opinions. Some lauded the Red Sox for addressing an area of need with an elite option. Others criticized the deal for giving up too much for an inherently low-value position. Many fell somewhere in the middle. I lean more towards the first group, and while I certainly see where those who disagree are coming from, there is one particular argument that strikes me as being particularly off base.

Among the dissenters of Dave Dombrowski’s first major move in Boston’s front office was Keith Law. As I said above, I understand many of his criticisms. Here is a sentence I do not agree with.

Craig Kimbrel has been one of the best relievers in baseball history, but this is a big overpay for 60 innings of his services a season when he already seems to be starting to decline.

Specifically, I have an issue with the idea that Kimbrel is starting the decline phase of his career. Looking a little deeper into things, calling for him to continuously get worse appears to be premature.

In 2015, Kimbrel appeared in 61 games spanning 59-1/3 innings for the Padres. In that time, he pitched to a 2.58 ERA, 142 ERA+ and 2.68 FIP while striking out 36.4 percent of his opponents. As good as those numbers look at face value, each represents a career low by a somewhat significant margin. So, decline, right? Case closed? Not really.

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The biggest reason for the worse numbers was a major increase in home runs allowed last season. Kimbrel gave up a long ball to 2.5 percent of his opponents, 0.9 percentage points higher than his previous career-high. His home run to fly ball ratio came in at 10.3 percent, 3.5 percentage points higher than his previous career-high. I’m not the biggest believer in the rationalization behind numbers like xFIP, but the idea that abnormally high home run totals can be fluky in nature has some merits. What’s particularly weird about this is the fact that it was the 27-year-old’s first season pitching in San Diego, a notorious pitchers’ park. Or, at least what’s usually a notorious pitchers’ park. You see, Kimbrel wasn’t the only Padres pitcher that had some weird home run spikage. Only the Yankees’ pitching staff allowed a higher home run to fly ball ratio in all of baseball. That’s not to say Boston’s new closer takes no blame in his home run spike, but there seems to be something else going on here. Whether it’s them moving the fences in some at Petco, some strange weather phenomena or something else, it appears there’s outside factors at play.

Even if you want to put all of the home run problems on Kimbrel, there are other numbers that suggest that he is just as good as he was the year before. Baseball Prospectus unleashed some new pitching statistics earlier this year — DRA and cFIP — that take in all of the factors in a pitchers success and try to find a true talent level. Unsurprisingly, DRA tracks with ERA and cFIP is associated with FIP. In other words, DRA is descriptive of the year that was and cFIP is predictive of the years to come. Kimbrel put up a 65 cFIP (100 is average, anything under is above-average) in 2015, two points better than his 2014 mark and the tenth best among all pitchers with at least 10 innings pitched this season. This suggests he should have some more 200+ ERA+ and sub-2.00 FIP seasons under his belt.

Looking at some more simple numbers, Kimbrel’s ability to strike batters out has hardly wavered. Sure, he’s not going to match the 50.2 percent K-rate he put up in 2012, but that’s something only one other pitcher (Aroldis Chapman) has done in the history of the game. He’s still setting down over a third of his opponents with ease, though, which is the mark of an elite talent. On top of that, his swinging strike rate came in safely above his career-average in 2015. A big reason for this is an increase in velocity for the flamethrower. This past season, his fastball averaged 98.4 mph per Brooks Baseball, the highest velocity of his career. He also didn’t wear down as the season went on, as he was still over 98 mph on average in September. In addition to all of that, his walk came in at 9.2 percent. It's not a hugely impressive number, but it's better than it was in 2014 and is on par with his career average. None of these things indicate a pitcher who is in his decline.

Really, the best argument you can make for Kimbrel being in his decline is the fact that every reliever is in his decline given their volatility, but that’s a lazy argument. Sure, random pop-up setup men who have one or maybe two good seasons can easily fall from grace at a rapid rate, but you rarely see that from the truly elite relievers. Look at some of the best relievers of the last 10-15 years. Yes, you have the Eric Gagnes of the world in there, but they're outweighed by the likes of Francisco Rodriguez, Billy Wagner, Troy Percival, Trevor Hoffman and, of course, Mariano Rivera, among others. These are all players who have had, or are still having, good and long careers. The best of the best don’t fall off like the mere mortals do.

If you want to say that Kimbrel isn’t going to be the same player he was in 2011 and 2012, that’s fine. He was literally the best reliever of all time during that stretch, and he’s not that anymore. However, that’s a loose definition of the word decline. Even in a down year, he was still an elite reliever in 2015, and that was with some weird home run results. His velocity is trending upwards, he’s not walking any more batters than usual and he’s still striking them out at an absurd rate. Most importantly, he’s only going to be 28 next year, putting him firmly in his prime. There’s little reason to believe we’re going to see anything but greatness from Kimbrel over the next few years in a Red Sox uniform.