Cubs by the Numbers: SIERA Illustrates Pressing Need for Better Pitching
There are a few different metrics that can give a clear look at a pitcher and his skill level. FIP (Fielding Independent Pitching) and xFIP (Expected Fielding Independent Pitching) are two that jump to mind when evaluating a pitcher’s performance over the course of the season. But SIERA, a newer stat, may give an even better illustration of how good a pitcher has been over a season.
SIERA is different than those other two stats because while FIP and xFIP include only strikeouts, walks, and home runs, SIERA includes all batted balls. On its most basic level, SIERA takes walks and strikeouts into account and adds in balls in play to give the complete picture and one that, as FanGraphs puts it, “accounts for some of the complexity of pitching.”
SIERA values the strikeout quite a bit, with the justification that those pitchers that strikeout a good number of hitters probably also generate weaker contact. Walks are bad, but as long as a pitcher doesn’t give up too many then it isn’t too bad. This obviously makes a lot of sense; fewer base runners equals less of a chance of giving up runs.
The balls-in-play portion is pretty complicated though. It looks at a variety of information: BABIP, Fly-ball %, Ground-Ball % HR/Fly ball, K%, BB%, etc. The higher the number of ground balls a pitcher gets, the better chance those have of being turned into outs. Double-plays also factor in because of the boost they provide to situational pitching.
On the flip side, a pitcher that gives up fly balls but keeps them in the park would be rated better than one that gives up more home runs/fly. SIERA takes the whole context of what a pitcher does and gives you a nice ERA-like number that is more accurate and can better predict future success.
FanGraphs does give an estimated chart, but do remember that league-average SIERA varies year to year because the performances vary year to year.
| Rating | SIERA |
|---|---|
| Excellent | 2.90 |
| Great | 3.25 |
| Above Average | 3.75 |
| Average | 3.90 |
| Below Average | 4.20 |
| Poor | 4.50 |
| Awful | 5.00 |
One of the most useful things to do with SIERA is to compare it to a pitcher’s ERA, FIP and xFIP to see if they were consistently good or just consistently lucky. It is one thing for a pitcher to win the ERA title, but it is quite another to have that pitcher win it based on luck instead of actual dominance.
Case in point: in 2010 Clay Buchholz had a 2.33 ERA (good enough for 2nd place in the AL), but a 3.61 FIP, 4.07 xFIP and a SIERA of 4.27. To the casual fan, Buchholz had a great year; he won 17 games and had a sparkling ERA. But an astute baseball exec or fantasy baseball geek, really anyone who might invest in Buchholz after that year, would probably hesitate before anointing him a stud pitcher.
With all of that in mind, now is a good time to look at some Cubs performances from 2014. Note that relievers generally have a lower SIERA score than starting pitchers; FanGraphs says a reliever that converted from a starting role will see their SIERA drop .37 points, and vice versa.
Let’s take a look at the best relievers first:
| Player | ERA | FIP | xFIP | SIERA |
| Pedro Strop | 2.21 | 2.66 | 2.82 | 2.59 |
| Hector Rondon | 2.42 | 2.26 | 2.81 | 2.60 |
| Blake Parker | 5.14 | 3.28 | 3.12 | 2.60 |
| Neil Ramirez | 1.44 | 2.61 | 3.48 | 2.82 |
| Justin Grimm | 3.78 | 3.20 | 3.63 | 3.18 |
| Wesley Wright | 3.17 | 3.44 | 3.80 | 3.65 |
Based on this information, Pedro Strop was the best reliever, performance-wise. Blake Parker was included on this list, not because I think he will be an important part of the pen going forward, but because he is a perfect example of the value of this stat. He had a pretty high ERA, but that was more indicative of some bad luck (.350 BABIP) than it was bad pitching.
All of these arms are above average and most of them are rated excellent by FanGraphs’ standard for the SIERA stat. Strop was absolutely outstanding in 2014 and his career SIERA number was 3.34. While that isn’t as good as this year, it’s still above average, which gives hope that this year may have been a step forward.
Hector Rondon showed some great results from 2014 and, rightfully so, will probably be the closer heading into 2015. If he can continue to stay healthy the Cubs may have a very affordable and dominant long term piece for the pen.
Okay, so how about the rotation?
| Player | ERA | FIP | xFIP | SIERA |
| Jake Arrieta | 2.53 | 2.26 | 2.73 | 2.83 |
| Tsuyoshi Wada | 3.25 | 3.75 | 3.96 | 3.89 |
| Kyle Hendricks | 2.46 | 3.32 | 3.92 | 4.06 |
| Edwin Jackson | 6.38 | 4.44 | 4.09 | 4.23 |
| Travis Wood | 5.03 | 4.38 | 4.51 | 4.41 |
| Jacob Turner | 7.12 | 4.78 | 4.49 | 4.85 |
This group was not great at all in 2014. Anyone not named Jake Arrieta was less than average. These results really highlight how great a year Arrieta had and how much excitement there should be over his outstanding performance. He was head and shoulders better than anyone else on the staff.
This also highlights a couple other key points; first of all, it is extremely possible that Kyle Hendricks success may not be completely sustainable. SIERA does value the strikeout pitcher a little more than a contact pitcher and I don’t think anyone views Hendricks as more than a back-of-the-rotation guy, but the dominant run he had to start his MLB career may be fleeting.
The other point these numbers show are how much an infusion of arms is needed for the team this offseason and next. So how about some of the Cubs’ targets and how they look?
| Player | ERA | FIP | xFIP | SIERA |
| Max Scherzer | 3.15 | 2.85 | 3.12 | 2.98 |
| Brandon McCarthy | 4.05 | 3.55 | 2.87 | 3.00 |
| Jon Lester | 2.46 | 2.80 | 3.10 | 3.09 |
| Jordan Zimmermann | 2.66 | 2.68 | 3.10 | 3.15 |
| Cole Hamels | 2.46 | 3.07 | 3.21 | 3.29 |
| Jason Hammel | 3.47 | 3.92 | 3.57 | 3.50 |
| James Shields | 3.21 | 3.59 | 3.56 | 3.59 |
| Justin Masterson | 5.88 | 4.50 | 4.08 | 4.03 |
Almost all of these pitchers would represent an improvement to a very weak pitching staff. Brandon McCarthy continues to be a sneaky-good target for the Cubs to take a chance on for 2014 and beyond. Lester would be great, but not as great as his contract is going to dictate; I’m afraid that the bidding is going to get out of hand for him very quickly.
Zimmermann and Hamels are trade targets and either one would quickly solidify a formidable top of the rotation with Jake Arrieta, but the cost in terms of prospects may be a little too high for the taste of the Cubs’ brass. You never know though. I still can’t see the acquisition of Tommy La Stella as anything more than a precursor to something else.
A Jason Hammel reunion would not be a bad thing either, and if Justin Masterson can reclaim his 2013 brilliance (SIERA of 3.32) then a flier on him would not be regrettable. In my opinion it will take at least one of these arms, if not two, to bolster a rotation that has some good pieces but as a whole is quite underwhelming.