Introducing the 2019 Astros: The Bullpen

The Houston Astros not only had the best rotation in baseball last year. they had the best bullpen too. The lowest ERA, the lowest FIP, xFIP, SIERA, the best WHIP. They had the sweetest DOOWOP, coolest BEBOP, the highest R-E-S-P-E-C-T factor, you name it.

OK, the first five were really true.

Will the Stros’ pen repeat as World’s finest in 2019? Let’s look.

The 2018 Bullpen

Here’s the group that started the 2018 season:

Ken Giles: ERA 4.99, 0.7 fWAR

Hector Rondon ERA 3.20, 1.3 fWAR

Chris Devenski ERA 3.97, 0.0 fWAR

Will Harris ERA 3.49, 1.1 fWAR

Brad Peacock ERA 3.55, 0.5 fWAR

Joe Smith ERA 3.74, 0.2 fWAR

Tony Sipp ERA 1.86, 0.9 fWAR

Collin McHugh ERA 1.99, 1.4 fWAR

By the end of the year Giles and Devenski were out, and Roberto Osuna and Ryan Pressly were in. Osuna added 0.6 fWAR in 22 innings and Pressly 1.0 in 23 innings.

In total, the bullpen was credited with 7.7 fWAR in 2018. The pitchers listed above accounted for 6.5 of those. The bullpen ERA was 3.03.

Relievers from last year Brad Peacock and Collin McHugh are slotted to the rotation for the time being in 2019 so we must subtract their WAR contributions. With Giles and Tony Sipp gone, and Joe Smith injured as well, the Astros bullpen must find 3.2 wins to replace the lost contributions of all these players.

It is notoriously difficult to predict the performance of bullpen specialists. They tend to vary greatly year to year, even month to month. Because of this I’m going to take a different approach to this topic than I have in the earlier articles. I will list various professional projections and average the results. And then I will just accept their findings.

The projections predict regression by the Astros bullpen. The ERA of these pitchers averaged together is 3.64, not an exact comparison to the overall bullpen ERA of 3.03 in 2018, but gets us a ballpark comparison. None of these pitchers are projected with an ERA below 3, whereas last year McHugh, Sipp and Pressly accomplished ERA’s below 2. And these pitchers only produce 5.1 fWAR compared to last year’s bullpen total of 7.7.

And the 5.1 is probably too high for this group. Valdez and James are considered starters in these projections and therefore have elevated WAR because they have too many innings for a reliever.

Of course, other pitchers will pitch relief for the Astros, although it is hard to say who, or how much. They will undoubtedly add to the WAR total, but probably not have a positive impact on the ERA.

Perhaps one or two of the rookie arms will add a spark to the 2019 pen, although the projection services do not predict that any of the young guns will surrender fewer than 4 runs / 9 innings. And of course trade deadline additions could help, just like last year.

I don’t completely trust these projections, especially for relief pitchers, but they give us the best estimate available. And so, expect regression from the Astros bullpen in 2019, very roughly a half run higher ERA, and around 2 less WAR. But if the Astros bullpen produces in the 3.60 ERA range, that would still make it a top 10 bullpen in MLB.

I said I wouldn’t do this, but if you’re like me, you might be wondering why Osuna and/or Pressly aren’t given more credit by the projections. Pressly’s ERA with the Astros last year was 0.77. So here is the first poll question.

Second question: