2018 Pittsburgh Pirates Rewind: The Starting Rotation

The Pittsburgh Pirates starting pitchers had periods where they flashes and periods in which they floundered.  The pitching as a whole was the youngest unit in the league in 2018, and this offseason they likely won’t make any changes.

The Pittsburgh Pirates built their 2013-15 playoff run on the backs of starting pitching, but this years past staff was a little different from the ones seen four years ago.  The club started off by trading away Gerrit Cole, acquiring three players at the Major League level and a prospect.  Cole turned in an impressively strong season in which all it took was throwing more of his breaking pitchers, the thing almost everybody saw coming.

That propelled his good friend Jameson Taillon to the front of the rotation and put more pressure on everybody else.  The club also acquired Chris Archer at the deadline, something they haven’t done.  In exchange, they traded away the pitcher who was supposed to go along with Taillon and Cole at the front of the rotation for many years in Tyler Glasnow, along with two other prospects.

Without Cole and with the addition of Archer, here’s, in terms of suppressing runs, how the 2018 Pirates rotation did:

The Pirates had two starters have sub 4.00 ERAs, with average starters (4.19) rounding out the rest.  Some of the advanced numbers (DRA and FIP) show a similar picture, and give a brief glance at who over performed and underperformed their ERA when trying to control for the pitcher’s actual ability to suppress runs.  Looking at the value a pitcher has provided, using the WARP framework, the starters ranked:

Jameson Taillon was the most valuable, partially because of the volume, and he was marvelous this season, posting a 3.20 ERA, 22.8 percent strikeout rate, 5.9 percent walk rate, and 10.7 percent swing and miss rate.  It’s that swinging strike rate that is most promising, especially after 2016 and 2017 campaigns of 8.3 percent and 8.2 percent respectively.

From May 27th and on, the date in which he Taillon really began to throw his slider, he posted a 2.71 ERA, 3.20 FIP, 23.1 percent strikeout rate, and 11.4 percent swinging strike rate in 22 starts.  That’s the encouragement heading into next year with Taillon, as he now has three pitchers (fastball and curveball) that can play.

Joe Musgrove was a 2.5 win pitcher despite only 19 starts, and he looked like a middle of the rotation of the arm when healthy.  He struck out 20.6 percent of hitters, a number you’d like to see go up in the future, but he also only walked 4.7 percent of hitters, showing a remarkable ability to control the ball.

Williams being only worth two wins might be a surprise, given his 3.11 ERA and 3.38 RA9, but he only struck out 18.0 percent of hitters, walked 7.9 percent, got a swinging strike at a 7.9 percent clip, and only averaged 5.5 innings per start.  Williams was a beneficiary of luck this past season, given the lack of swing and miss in his game, but that doesn’t diminish his value of what he provided to his going forward.

Baseball Prospectus’ pitcher WARP is based on of DRA, or deserved run average, which tries to explain what a pitcher should have allowed.  Musgrove’s DRA in 2018 was 3.43 compared to Williams 4.28, breaking those down into components where negative is always better and the components are counting numbers, we see that:

Not In Play Runs, NIP Runs, is defined as “compile the results of models for unintentional walks, intentional walks, hit-batsmen, and strikeouts… They are also by far the most valuable contributions a typical pitcher makes to run prevention.”  This is the area in which Williams has struggled throughout his career, and not missing bats presents more opportunities for batters to reach base.  Musgrove’s strikeout rate was 2.6 percentage points higher and his swinging strike was 3.5 percentage points higher, as he allowed less contact and ball in play moments than Williams.  That’s a big key difference in their overall contributions to the Pirates in 2018, as Williams had to rely on his defense more often.

Hit Runs is defined “measure the pitcher’s ability to minimize damage on pitches that end up being hits of some kind.”  Both Williams and Musgrove were about average here, as 35 percent of Williams hits were extra bases and 30 percent of Musgrove’s were extra base hits.  The league mark was 36 percent, so it’s easy to see how both were around average, and Musgrove was a bit better than Williams.

Finally, there is Out Runs, which “refer to the pitcher’s ability to generate typical outs on balls in play, usually by generating weak or directional contact.”  This is where Williams excels, as he ranked 25th in average exit velocity against among pitchers with 150 batted ball events at 85.6 miles per hour.  He got soft contact at a high rate, and that generated his success.  Musgrove too generated weak contact, as batters had an average exit velocity of 86.9 mph off him.

The large difference in trying to figure out who contributed to the Pirates, came in terms of the swing and miss.  Musgrove was much better, and on individual value that matters, especially going forward.  Williams prevented runs, the 3.11 ERA proves that, and there’s no taking away from that run suppression.  He just did so in a way that relies on some luck, something that may not be there going forward.  Being a two win pitcher with a 4.28 DRA is still around an average starter, that’s nothing to scoff at, and the work he showed in the second half was tremendous.  Average starters who can stay healthy and provide innings are very valuable.

The veteran Ivan Nova was the fourth most valuable starter, being worth just over a win in his time.  While he doesn’t miss bats – a 16.7 percent strikeout rate and 8.8 percent swinging strike rate – Nova doesn’t walk batters, posting a walk rate of 5.1 percent in 2018.  What Nova does bring is a pitcher who you can rely on for making almost all of his starts, and he’s tossed more than 160 innings each of the last three years.

While he’s one of the highest earners on the club, Nova doesn’t match that value, perhaps his leadership (a non-quantifiable, but valuable skill for a young staff) provides more than meets the eye.  But he doesn’t need to be a 3.0 win pitcher to match his contact, being a backend guy for $9.167 million isn’t the worst result, and he filled the role of a veteran on the youngest pitching staff in baseball last year.  He’s a justifiable five starter.

Then, finally, to round out the club’s starting rotation to end the year is Chris Archer, who has disappointed over the last three seasons, especially on the surface level.  This is how Archer has performed over the last four years:

Archer has seen his ERA get worse every year, and his underlying numbers in 2018 weren’t promising he was that much better than the surface numbers.  His 4.30 DRA was average, and the Pirates are better he’s more than average considering the package they traded for him.  Archer’s 2015-16 strikeout rate of 28.6 percent fell to 25.4 percent, the strikeouts didn’t come despite the 13.1 percent swinging strike rate, which might be the good part.

Looking at the 2980 pitcher seasons since 2010 to have thrown at least 50 innings, they’ve produced the following swinging strike and strike out rates:

The model ends up being: KRate = 0.02+1.92*SwStrRate, so plugging in Archer’s swinging strike rate of 13.1 percent, Archer should have had a strikeout rate of 27.2 percent, 1.8 percentage points higher than his rate in 2018.  That should lead to some hope into next year.  But it’s not just Archer that should see a bump, Musgrove’s 11.4 percent swinging strikeout comes out to a 23.9 percent strikeout rate in this model, 3.3 percentage points higher.

Archer should have gotten more strikeouts based on the rate he got batters to swing and miss, that’s a positive.  But in practice, be it on pitch selection or some bad luck, he didn’t, and that’s part of the reason for why he was worse off.  Add in that 38 percent of hits he allowed were extra bases, and you can begin to see where things went south.  He was average in 2018 and the underlying numbers support that.  Next year, the Pirates need more than average from Archer, they need the top of the rotation Archer to compete for the division and the playoffs.

Chad Kuhl, once again, looked like he could be a relief weapon or potentially a backend starter.  He struck out 21.7 percent of hitters while walking 8.9 percent, the league average among starters was 21.6 percent and 8.0 percent.  While his DRA in 2016 and 2017 were far below average, this past season his 4.24 was more inline with an average starter.  Unfortunately for Kuhl, his season was cut short and after alternative attempts, he underwent Tommy John surgery,  The right-hander will miss all of 2019 and return for his age 27 season, at which point the relief option might be the best bet given rotation constraints, evolution of the starting pitcher, and the coming back from surgery.

Nick Kingham made his debut this season, and the first start was about as perfect as one could get.  Unfortunately for him, the rest of the season wasn’t.  Kingham posted a 5.21 ERA and his estimators weren’t much better, and he was below a replacement level player this season.  Given the rotation looks set and no options remaining, Kingham and the Pirates are an interesting spot going into 2019.  If he remains on the roster, it’ll likely be in long relief duty.

Clay Holmes made four starts, with his third being surrounded with some bits of controversy, especially after he allowed seven runs.  In total, he only pitched 26.3 innings, but the Pirates got -0.6 wins between him and Kingham, the two depth pieces that started the year in Triple-A.  Holmes wasn’t good this past year, and he walked more batters (17.8 percent) than he struck out (16.3 percent).  But he does have an option remaining, and so he’ll likely be back with the club and start the year in Indianapolis.

The Pirates pitching staff was good in parts of 2018 and bad in others, and collectively their starting pitching ranked 12th in baseball this past season in ERA.  Heading into 2019 the club needs Taillon to keep pace with the level he showed after he added a slider.  Musgrove, who underwent surgery this offseason, needs to stay healthy as he showed some promise and his swinging strike rate indicates there should be more in terms of strikeouts.  Archer should be better, but that’s been a trend for the last three years.  Williams will regress and likely be an average starter given his ability to induce weak contact.  And Ivan Nova will round out the rotation as a five starter.  There’s still potential in this group, but next year, I’d expect them to be somewhere in the 8-12 range again in ERA.

*Numbers from Baseball Prospectus, Fangraphs, and Baseball Savant

2018 Pirates Rewind:

• Data Visualizations
• The Catchers
• The Infield
• The Outfield