Identifying the greatest weakness of each Red Sox starter

At separate points throughout this season, different starters in the rotation have been at least somewhat reliable if not outright effective for the Boston Red Sox. Unfortunately, those stretches haven’t lasted long enough and have rarely come in concert with equally strong showings from the other arms in the rotation.

As the Red Sox’ title defense continues to crumble around them, the starters have done a bulk of the demolition but the reasons behind each starter’s struggles are not all the same. Among the myriad issues that have plagued the staff, these are some of the more troubling ones facing each of the players in the regular rotation.

Chris Sale - Failing to strand runners

Any discussion about the downfall of the Red Sox’s rotation has to begin with Sale. The ace of the staff and a regular preseason pick to win the Cy Young award, Sale has been anything but the strike-throwing superhero he’s been in year’s past.

Among the many areas in which Sale has struggled, his ability to get out of jams has really taken a hit. He is currently stranding only 66.8 percent of the batters that reach base. While his ballooning home run and walk rates are certainly scary sights as well, his inability to buckle down and get outs when it matters most is only making things worse. Prior to this season, Sale had stranded at least 73.2 percent of base runners in every year of his career, including a staggering 82.5 percent just last season.

The phenomenon reared its ugly head during Sale’s most recent start against the Yankees. After trading two singles and two outs to start the fourth inning, Sale allowed five-straight hits, including a three-run home run to DJ LeMahieu before being taken out of the game.

Sale’s troubles in this area can be partially blamed on the fact that he has had worse luck than usual (.319 opponent batting average on balls in play) while his fastball has become a slower pitch that has been less effective and less often utilized, essentially removing an arrow from his quiver that usually helped him get out of tough spots. There are clearly plenty of things Sale needs to do to become the pitcher he was before this season, but finding ways to get outs in critical spots should be at the top of the list.

Eduardo Rodriguez - Letting up home runs

Although Sale is the ace of this staff, that is largely a nominal title this year. Rodriguez has actually been the best starter on the roster, with an ERA+ of 116 entering his start on Wednesday that led all Red Sox pitchers who have started at least five games. You can point to a noticeable dip in his strikeout rate and strikeout-to-walk percentage but the really glaring weak point has been his tendency to give up home runs. That is certainly not a weakness unique to the left-hander, but 14.8 percent of the fly balls Rodriguez has surrendered have ended up over the fence. That’s up from 11 percent a year ago and is easily the highest mark of his career. When you combine it with more players reaching base due to walks, that is a recipe for disaster.

Rodriguez’s propensity for giving up home runs was most apparent in June when he was tagged for eight long balls in 37 innings across six starts. He has been more effective since July started, particularly during gems against the Dodgers and Rays, but with a home run to fly ball percentage of 13.2 in his last seven starts, which is still above his career mark of 11.8 percent, the problem clearly hasn’t disappeared entirely. On the bright side, Rodriguez’s fly ball rate is the lowest its been since 2015 but when opponents are able to get some air under the ball, it has been more dangerous than usual for the southpaw.

David Price - Avoiding hard contact in the second half

Price has been a better than league average pitcher in every year of his Red Sox career even if the narrative around him might say otherwise. However, this season has clearly been one of his worst as a Red Sox, at least based on traditional metrics. If his current 4.36 ERA held for the rest of the season, it would mark the first time in his Boston career that he has posted a mark above 4.00. When you take a deeper look, you’ll find that he actually has a better mark in FIP this season (3.65) than last year (4.02) but that hasn’t mattered because he has been allowing too many players to hit the ball hard.

Even though his ground ball rate is up, Price has been both a victim of bad luck and his own struggles with avoiding the barrel of the bat. Opponents are hitting .338 on balls that are put in play against Price but that doesn’t make up for the fact that his hard hit rate (37.2 percent) is higher than its ever been in his career. Things have become particularly dicey in the second half of the season, with that hard hit rate rising to 43.5 percent compared with a mark of 35.3 percent in the first half. Unsurprisingly, that has yielded ghastly results, with Price’s ERA above 8.00 in his last 22 innings pitched. There is much more evidence of Price pitching effectively this season, but now that the second half has hit, it has hit him hard.

Rick Porcello - Losing his slider and strikeouts

Porcello has never been a strikeout pitcher in the same way as Sale. Even during his Cy Young campaign in 2016 he only struck out 7.6 batters per nine innings. But in this environment where strikeouts are constantly rising, Porcello is doing himself a disservice by not producing more punch outs and this season that has really taken a toll. His 18.2 strikeout percentage is the the lowest mark of his Red Sox career and the the lowest he’s produced since 2014. It has only run in parallel with fewer groundballs and fewer runners left on base.

The real culprit for this occurrence would appear to be his slider, which has been a much less effective pitch this year than in the past. That has caused him to turn away from the offering a bit more frequently and rely more heavily on his fastball. That would be fine if Porcello was distributing heat but with his fastball velocity hovering around 91 to 92 miles per hour, its not the type of pitch that will overpower hitters and because of that, Porcello just isn’t getting the strikeouts he needs.

Andrew Cashner - All those home runs

You can argue that the weaknesses that have been identified for some of the starters above are not the most pressing, which is why the starting pitching has been so awful. If there are so many options it means a lot is going wrong. However, for Cashner, at least during his time with the Red Sox, the answer is exceptionally obvious.

Diving a little deeper, one of the more striking problems Cashner has had has been with his changeup. It is his second-most utilized offering behind his fastball and one that had a 14.6 mark in FanGraph’s pitch value metric when he was with the Orioles this season. However, since he traded Baltimore orange for Boston red, Cashner’s changeup has sunk in effectiveness and Cashner’s performance has gone along with it.

All statistics courtesy of FanGraphs and Baseball-Reference.