Statistical analysis explains dominant Red Sox pitching in race for the top spot in the division
This was a big week for Red Sox pitcher Rick Porcello, who collected his league-leading 21st and 22nd wins of the season, which included a complete game against division rival Baltimore Orioles. With those 22 wins, along with a 3.11 ERA, 183 strikeouts and 5.0 wins above replacement (WAR), Porcello is having by far the best season of his career. He is putting himself in Cy Young contention a year after having perhaps the worst season year of his career.
For Red Sox fans and those who have followed his career since his debut with Detroit in 2009, this leap to seemingly ace status after a productive but by no means great first-seven years in the league is likely confounding. Through the aid of advanced stats, the answer to this question becomes a bit more evident.
Porcello’s advanced batted ball and plate discipline stats per Fangraphs do not jump off the page as significantly different from those in other years of his career, but real differences do exist.
In terms of the similarities, while Porcello has struck out a career-best number of batters, his strikeout rate is actually lower than it was last year (7.59 percent this year to 7.80 percent last year). However, it is more than a percentage point higher than it was for much of his time in Detroit.
In addition, his groundball rate is also lower than it was last year (43.8 percent to 45.7 percent) and significantly lower than earlier in his career. These stats are particularly surprising given his current career year, as inducing strikeouts doesn’t require anything of the defense and, as such, doesn’t create the potential for a hit or homerun. Groundballs are also easier for the defense to convert into smooth outs and quick double plays relative to hard line drives and easy fly balls.
Expectedly, Porcello has incurred by far the highest fly ball ratio of his career, with it thus far at 37.4 percent relative to last year’s previous career high of 32.5 percent. Essentially, Porcello is striking out batters at a lower rate, getting fewer groundballs and giving up more fly balls than his career-worst year last year, which on the surface seems like a recipe for disaster. So how is this his career best year?
One notable element of Porcello’s performance has been his walk rate. After last year’s 5.2 percent rate, which ranked him a more-than-respectable 15th in the majors, he has been able to cut that down to an elite 3.5 percent, ranked second in the major leagues.
In addition to not giving batters a free pass and putting them on, he’s also dropped his home run rate from 1.31, a lowly 69th in the league, to 0.91, good for 12th in the majors. It’s possible that this has been the product of luck, particularly given his elevated fly ball rate and similar hard hit percentage (32.8 percent last year to 30.1 percent this year, ranking this season at an above average 25th), as he can’t control how far the ball goes when it is hit in the air.
While the difference between the walk rates only amounts to eight fewer batters, this is critical over the course of 45 more innings. This stat contributed to his significantly improved walks plus hits per inning pitched, which went from 64th to 3rd this season. Overall, Porcello has been able to keep people off the bases and avoid giving up homeruns in a way he wasn’t even close to last year, leading to the incredible success he’s had this regular season.
With the season coming to a close, the Red Sox will hope that Porcello can continue his dominant pitching. The Sox are looking at a division victory if they can stave off rivals Toronto Blue Jays.