Chicago Cubs analysis: Pause and think before signing Arrieta to a multi-year extension

Oct 18, 2015; New York City, NY, USA; Chicago Cubs starting pitcher Jake Arrieta (49) talks with catcher Miguel Montero in the third inning against the New York Mets in game two of the NLCS at Citi Field. Mandatory Credit: Anthony Gruppuso-USA TODAY Sports

Before the Chicago Cubs sign Arrieta to a long-term contract, they need to consider his postseason performance.

Despite his historic numbers during the regular season, Arrieta faltered during the postseason. After a complete game, scoreless gem in the National League Wild Card game, Arrieta struggled in his next two postseason starts. In Game 3 of the National League Divisional Series, Arrieta pitched 5.2 innings and surrendered four runs on five hits. In Game 2 of the National League Championship Series, Arrieta gave up four runs on four hits in five innings of work. His overall ERA during the playoffs was 3.66 which was dramatically worse than his regular season ERA.

Lets put these numbers in perspective for a moment. The last time Arrieta didn’t make it to the sixth inning of a game was June 16th against the Cleveland Indians. The last time he gave up four or more starts was in that same game. During the regular season, Arrieta gave up a total of four runs in twelve starts spanning from August 4 until his last start of the season on October 2.

So what happened? Can we chalk up the dramatic reduction in effectiveness to just two random bad starts that happened to occur back-to-back? Did the playoff pressure get to him? If so, how was he able to pitch a shutout in a crazy atmosphere in Pittsburgh then let the moment in the next two games get to his head? Advanced statistics suggest that a tangible, underlying issue caused Arrieta’s struggles in the playoffs.

Oct 12, 2015; Chicago, IL, USA; Chicago Cubs starting pitcher Jake Arrieta (49) is taken out of the game by manager Joe Maddon (70) during the sixth inning against the St. Louis Cardinals in game three of the NLDS at Wrigley Field. Mandatory Credit: Jerry Lai-USA TODAY Sports

According to baseball reference, Arrieta pitched 229.0 innings in 33 starts during the regular season in 2015. His previous highest total came in 2014 when he pitched 156.2 innings in 25 starts. In the 2015 playoffs, he pitched 19.2 innings. When his regular season inning total is added to the 19.2 innings that he pitched in the postseason the sum comes out to 248.2 which is almost 100 more innings than he has ever pitched during a single season in his career.

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Advanced statistics courtesy of Brooks Baseball suggest that fatigue due to the high inning total was a major cause of his sub-par performances at the end of the season.

In his Game 2 start against the New York Mets in the National League Championship Series, Arrieta struggled to get velocity on his pitches. His fastball, slider and sinker velocities were about one MPH slower than his regular season average. Three out four of the Mets’ hits off of Arrieta came on one of these pitches.

In Game 3, velocity was an issue again. His sinker was about half a mile slower than average and his slider was one MPH slower than average. It is also worth noting that he threw his sinker 59 times which explains some of the overall velocity issues in this game. Five out of the six hits that Arrieta surrendered came on these two pitches.

In both games, Arrieta’s command was an issue as well. He hung too many pitches up in the zone. It is difficult to objectively pinpoint command problems as a matter of fatigue or lack of focus or something else entirely. Regardless, here are strike zone plots of both games courtesy of Brooks Baseball.

Can Jake Arrieta perform at a high level in the postseason off of a high inning total in the regular season? If not, are the Cubs willing to put an innings limit on him or rest him at the end of the season in order to prepare him for the playoffs? The Chicago Cubs front office should consider both of these questions thoroughly before signing Arrieta to a long-term contract.

Next: Age is an issue