The big free agent signing by the Cubs front office this past season was signing Edwin Jackson to a 4-year, $52 million contract. Needless to say, it hasn't gone as Theo Epstein and Jed Hoyer had hoped, but it hasn't been all bad either.
In his first season with the Cubs, Jackson has allowed 5.67 runs per 9 innings to teams that have scored 4.28 runs per 9. According to Baseball Reference, Jackson has even been helped out by the defense just a bit. Baseball Reference has him being worth -1.1 rWAR over the season.
Baseball Prospectus is a little more kind than that. BPro's WARP uses FRA for pitchers and Jackson's FRA is 4.37, which is actually less than the 4.67 he had a year ago. His WARP is 0.6.
Fangraphs uses FIP for WAR and his FIP is actually pretty decent. His FIP is 3.72, which is an FIP- of 96. That's right in line with what he's done each year since 2009. His fWAR is 1.9
That's still less than what the Cubs were hoping to get. If we estimate the average win value over the four years of his contract at $6 million, that would mean the Cubs paid for about 8.7 wins. Due to Jackson being 29 this season, the Cubs likely expected him to produce those 8.7 wins over the next 4 years like this: 2.8, 2.4, 2.0, and 1.5 wins.
If we use his fWAR, he's come somewhat close to achieving that, but the Cubs were obviously hoping his runs allowed would better match his strikeouts, walks and home runs.
At the time of the signing, GW pointed out how Jackson turned down the best offer he could get after 2011 (Pirates, 3 years, $27 million) into a 4-year, $52 million contract a year later.
Edwin Jackson didn't like the offers he received last offseason, turning down 3 years, $27 million from the Pirates in favor of a 1 year, $11 million dollar deal from the Nationals. This type of "I'll try my luck next year" gambit almost never seems to pay off, but, wow, did it ever for Jackson. For me, the take home message is that smart baseball analysts won't hesitate to put a considerable amount of stock in a single season's worth of pitching stats. Jackson put up a career year with the Nationals, and the league believed in his numbers.
Edwin Jackson struckout 17.2% of the batters faced in 2011, but that jumped to 21.3% in 2012. That wasn't the first year he reached 20% (2010), but the rest of his seasons weren't particularly close to that mark. This season? 17.7% and a career 17.6% strikeout rate. His walk rate has been pretty consistent over the last three seasons. It was 7.2% in 2011, 7.3% in 2012 and it's 7.7% this season.
He's maintained a similar FIP despite the decrease in strikeouts. He's done so by allowing fewer home runs.
All in all, Jackson's numbers aren't as bad as they appear, but they aren't all that impressive either. They aren't worth the $52 million the Cubs signed him for, but I don't think we should expect him to allow this many runs next year either.
As I said, the strikeouts and walks are both in line with his career rates and he's maintained a consistent FIP- for 5 seasons now. His career HR/FB rate is 9.9% and it's 9.8% this year.
The difference in his home runs is the result of the types of batted balls he's allowed. He's allowed a career high 52.6% groundball rate this year and a career low flyball rate of 27.9%. He's never allowed fewer than 31.3% of the balls in play to be fly balls before this year. His career rate is 35.4%.
If you think his GB rate will remain about what it has been this year, I think we could safely expect him to have considerably better results next year.