The Cardinals' pitching should regress and that's okay

Regression and sustainability are often buzzwords in the sense that when we cannot explain a result that does not meet our expectations, it can be very easy to throw those words out, dismiss the current performance and then expect it to get better or worse to meet our expectations. When it comes to the St. Louis Cardinals' pitching staff, the team that is first in ERA by a mile at 2.60, first by a bit in FIP at 3.31, and first in fWAR by nearly a win over the second-place Washington Nationals words like regression and sustainability might be terms to be feared and ignored. Nobody wants to hear that they might not be quite as good as their performance indicated, but regression is not bad, it is just setting reasonable expectations.

For the Cardinals, this regression does not mean that the Cardinals's pitching is not good now, and it does not mean that it will not be good in the future. No rotation has averaged more innings per start and has more strikeouts per nine innings than the Cardinals' rotation. NIck Lampe took a look at sustainability in June and the Cardinals have kept on rolling. If the Cardinals go the rest of the way with a 3.86 ERA, they will be first team since the 1989 Los Angeles Dodgers to finish the season with an ERA under 3.00. Run prevention, which includes one of the better defenses in the league, has been an incredible asset for the Cardinals all season long, and even if the team regresses closer to expectations, they will still have done an incredible job this season.

Let's look at a few charts to illustrate regression. Here are some statistics for the the rotation:

The above statistics all look very good. Sub-three ERA for Lynn, Martinez, and Garcia with Wacha and Lackey hovering around three. The walks are not terrible and FIP is solid as well. All of the above numbers include regression. ZiPS rest of season projections, available at FanGraphs, are combined with what the pitchers have done so far this season to provide an updated end of the season projection. Looking at the stat line at then end of the season, would we believe that regression hit the team hard? Regression does not mean the team will get bad all of a sudden, and it does not invalidate the results that have happened thus far. The results that have happened inform the projections and in many cases provide for a more optimistic projection than one prior to the season.

This is what the Cardinals' starting staff has done so far this season.

Those numbers are all fantastic, but when you look, particularly at ERA, how many of those pitchers would you bet on matching or beating that ERA going forward the rest of the season? Not Garcia. Probably not Martinez or Lackey. Lynn beating a 2.76 ERA would be pretty optimistic. Maybe Wacha, if he keeps pitching well, can get under a 2.92 ERA, but every single ERA looks like an optimistic view of what we know about those pitchers. Expecting them to not perform quite as well as they have is not a pessimistic view, but a realistic one. That is regression.

Here are the rest of the season projections from ZiPS.

Repeating the exercise from above, we might reasonably take the under on several of these ERA's. The Cardinals have a fantastic defense, and it might be reasonable to expect them to beat their FIP, but based on what we know about these players from years past as well as this season, the higher ERA provides more reasonable expectations. The numbers in the last two charts combine to make the totals in the first one, which would be one of the best pitching staffs in the last several decades.

For the record, here are the rest of season projections for the bullpen, which has also been fantastic this season:

For some of you, this exercise might be a bit redundant while for others it may be intuitive, but it is important to note regression is not a bad thing to avoid discussing just because a team is performing well. It would be amazing if this team kept preventing runs just like they have for the first 111 games of the season the rest of the way, but to pretend like it is a reasonable expectation ignores too much evidence. Expectations shape the way we view and sometimes enjoy our experiences. To say anything other than that the Cardinals pitching staff has exceeded expectations so far this year would be false. Resetting expectations to a level that previously exceeded them beyond any reasonable level going into the season does not make a whole lot of sense. There's nothing wrong with setting reasonable expectations. That is regression.