This is far from an original thought, but the Red Sox rotation is confounding. That doesn’t mean it’s bad, per se, but it also doesn’t mean it’s good. Honestly, I have no idea what it is. I’m certain that David Price is good, but after that I just don't have a clue. I’m pretty sure Clay Buchholz is good, but I also know that he’s not going to be good for 30 starts in one season. I’m pretty sure that Eduardo Rodriguez has the potential to be quite good, but he still has steps to take to reach that next level. I’m pretty sure someone in the Joe Kelly/Brian Johnson/Roenis Elias/Henry Owens can step in and become a respectable member of a major-league rotation, but I don't know which one it will be and when he'll get the opportunity.
Then, there's Rick Porcello. For full disclosure, it should be noted that I was lower on him than most heading into last season, and obviously his 2015 didn't do much to change that perception. The Red Sox organization was clearly high on him prior to the season, and bet big on him. Not only did they trade Yoenis Cespedes — one of their bigger trade chips at the time — for him, but they handed him a long-term deal before pitching a game in Boston. Obviously that bet failed in year one.
By just about every reasonable measure, Porcello was a below-average pitcher in 2015. He finished the year with a 117 ERA-, a 104 FIP- and a 4.69 DRA. To his credit, he also managed a 98 cFIP, which is very slightly above average. However, it’s safe to say that his performance was well below the expectations set out for him. Even as someone whose expectations were relatively low, I was looking for something around a league-average performance. He finished the year below that line, and was significantly below it for most of the season. This, in it’s own right, is somewhat interesting. The Red Sox made a big bet, and lost. That’s a story by itself, but it’s one for someone else to tell (and they have). What I’m more interested in is why he struggled so much. The biggest answer to this question, of course, is dingers.
Before we get into the home run talk, let's take a quick look at the basic differences between his 2015 and the other seasons in his career, when he was consistently and boringly average. There is some connection between these issues and the homers. The first difference any quick look at his stat line shows is a big increase in his strikeout rate. After spending the majority of his career with a strikeout rate in the 13-15 percent range, Porcello struck out a full 20 percent of his opponents last season for the second time in his career. That should be a good thing, but it changed the other parts of his game that made him effective. Specifically, he stopped inducing ground balls. While this had always been a calling card, he finished 2015 with just a 47 percent ground ball rate, marking the first season in his career with a rate under 50 percent.
These two changes signal a change in strategy on the mound. He was no longer satisfied generating relatively damge-less grounders, instead opting for more strikeouts. A pitcher can survive giving up more hits in the air, as long as it’s under control. To put it mildly, Porcello did not have it under control last year. The now-27-year-old gave up a lot of hard contact in 2015, and even with all the other issues in his game, this was the true cause of his struggles. More specifically, he was killed by the long ball. He gave up 25 long balls last season, the most of his career and tied for the 18th most in all of baseball. His 1.31 home runs allowed per nine innings was the tenth highest mark for any qualified pitcher in the game.
So, the question moving forward becomes whether or not it was an anomaly or if it’s something to worry about for a long time. As these things typically are, it’s somewhere in the middle. ESPN’s Home Run Tracker has different designations of their home runs, and while it’s not the most scientific description it’s still plenty useful. So, with that caveat, seven of Porcello’s 25 homers allowed were called "no doubt" shots by ESPN’s tool. While that may not sound like a lot on its face, it’s more than all but five pitchers in baseball. On top of that, he gave up a ton of hard contact in general. His 14.5 percent HR/FB ratio could be construed as bad luck, but it’s also a sign that many of the fly balls he gave up were crushed. Furthermore, Fangraphs has their own metrics that measure strength of contact. According to that data, Porcello gave up the sixth highest rate of hard contact of all qualified pitchers in the game.
On the other hand, there is other data suggesting that this isn’t something to be overly worried about for the long-term. For one thing, as I mentioned before, a HR/FB ratio that high can be looked at as luck. I typically don’t agree with that kind of analysis, but it’s worth pointing out that some very smart people adhere to that argument. Moving back to the Home Run Tracker, another eight of the dingers allowed by Porcello were designated as "just enough." It’s not quite as high on the leaderboard as his "no doubt" ranking, but it’s still towards the top of the list. Finally, we look at his average fly ball distance allowed. When I was researching this, I fully expected him to be towards the top of this list, based solely on watching the majority of his starts. Surprisingly, the average fly ball allowed by Porcello travelled just over 280 feet, placing him almost directly in the middle of the pack.
So, there are good arguments to be made that he will continue to give up home runs, and there are good arguments to be made for the opposite. Even in the second half of the season, when he was pitching well, he was giving up homers at a career-high rate. My guess would be that he sees a decline, but not down to the 0.8-0.9 per nine innings rate he typically sat at. If he can get it down to one per nine innings, however, Porcello should get back to being a solid if unspectacular pitcher and help clear up some of this confusion in the Red Sox rotation. I'm pretty sure he can do that, but I'm not positive.