The St. Louis Cardinals traded for veteran starting pitcher J.A. Happ at the trade deadline last month.

At the time, most folks didn’t think much of the acquisition, as it didn’t look very flashy on paper.

However, Happ has surprised many fans with his performance in a Cardinals uniform.

He has made four starts so far, and he has allowed two runs or fewer in each of them.

But here’s the thing: Happ’s success with St. Louis might be an illusion.

Some complementary data suggests that he has been very lucky in his first four outings with his new team.

Let’s evaluate.

Happ’s Success With St. Louis Might Not Last Much Longer

As mentioned, Happ has made four starts with the Cardinals so far.

On the surface, it seems like he has been outstanding in all of them.

But actually, he’s extremely fortunate that his ERA looks the way it does.

Happ has a 1.99 ERA and 4.58 FIP with St. Louis.

For those who aren’t familiar with FIP, it’s essentially a predictive ERA.

In Happ’s case, his FIP is much higher than his ERA, which suggests that his numbers may balloon very soon.

FIP isn’t always perfect, but when there’s a difference of almost three full runs between a pitcher’s ERA and FIP, that’s a major red flag.

That’s what’s going on with Happ right now.

Happ Didn’t Pitch Well During The First Half Of The Season When He Was With The Minnesota Twins

Four starts is a relatively small sample size.

19 starts, however, is not.

The 38-year-old made 19 starts with the Minnesota Twins before he was traded to the Cardinals.

As we mentioned, when he was dealt, it was a low-profile trade.

The reason for that?

He didn’t pitch well at all during his time with the Twins.

The lefty posted a 6.77 ERA, 5.42 FIP, and 1.59 WHIP during his stint with Minnesota this season.

His FIP with the Cardinals is virtually identical to the FIP he posted with the Twins.

That’s extremely alarming.

In theory, that means that he isn’t actually pitching any better with St. Louis than he was with Minnesota.

His 1.99 ERA with the Cardinals is certainly very attractive, but fans shouldn’t expect that kind of production from him for much longer.

What Will St. Louis’ Rotation Look Like If Happ Regresses?

Regression from Happ feels inevitable.

Assuming it happens, will the Cardinals be able to over to overcome it?

Maybe.

When healthy, the team has a really solid rotation that consists of Adam Wainwright, Kwang Hyun Kim, Jack Flaherty, Miles Mikolas, and one of Jon Lester or Happ.

First and foremost, St. Louis needs to get healthy fast if it wants to steal a playoff bid.

But if the health issues subside, then the team has the depth to overcome Happ’s potential regression.

Happ could eventually be thrust into a long-innings relief role, or if his regression isn’t too intense, he could hold onto the No. 5 spot in the rotation.

It’s tough to predict at this point.

One thing is for sure, though: The Cardinals are currently 4.5 games back of a Wild Card spot, and they need to start making up some ground.

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