Pittsburgh Pirates: Evaluating Early Sample Sizes on Kyle Keller, Nick Mears

Photo Credit: MLB.com

There isn't any denying that the Pittsburgh Pirates have a lot of areas of opportunities across their roster. It would also be hard to deny that through all the struggling pieces, the bullpen has been one of the biggest areas of concern, especially of late.

It shouldn't really come as a surprise, especially since they traded their closer (Richard Rodriguez), and another regular in Clay Holmes. While the returns early on have produced positive results, it has left a hole in the bullpen Derek Shelton is still trying to figure out.

Two of the players that are going through the 'evaluation' stage is Kyle Keller and Nick Mears. While the Pirates traded for Keller at the beginning of the season, Mears - who was underrated - came up through the system. He's actually ranked as the Pirates 42nd ranked prospect according to Fangraphs.

Even though Mears appears to have more of a long term upside, the fact that Keller is still in Pittsburgh right now says that he could play himself into a potential roster spot going into next year.

So how have the two looked, and who potentially has a leg up on the other if all other things are considered even? I don't usually try and throw out a bunch of numbers, but decided to see how some of the analytics played in one or another favor and see if there is maybe more there.

Both are on smaller sample sizes, so it won't too well into any long term projections on either player but this is how they are looking early on.

Expected Stats

While it isn't the end all, be all, generally speaking if you are allowing your opponent to consistently hit the ball hard, it isn't setting you up for success. So on baseball savant, a lot of what the 'expected' metrics factor in heavily is exit velocity, among others.

It can kind of tap in, under the right conditions, is based off what kind of contact hitters are making with the ball if a pitcher is getting lucky, or unlucky with their results.

Nick Mears


Kyle Keller




















Exit Velocity



Hard Hit Swing %


While the basic counting results haven't really gone in Keller's favor, some of his underlying numbers are encouraging. His expected batting average is really good, one of the better marks on the team, and his xwOBA is way below his actual mark, meaning their could be room for improvement. 

That's not to mention that his expected ERA is almost three runs less than his actual mark. It could mean something. It might mean nothing, remember this isn't a big sample size we are dealing with.

Mears on the other hand, has been getting softer contact overall but his underlying numbers are all higher than what he's actually producing. So where as the numbers are leaning towards improving numbers for someone like Keller, those same statistics speak in the opposite for Mears.

Pitch Value

The next thing I wanted to look at was their individual pitch arsenal and how they are performing. 

Ok, so a lot of numbers to digest, so bear with me, I'll try to explain them the best I can. This is breaking down each of their fastball's value. Run Value per 100 measures just what it says it does, the value a given pitch has per 100 times they threw it. Anything on the positive side of the spectrum means you are costing the team, anything negative is good.


Fastball Metric






Whiff %



Strikeout %











As you can see their fastball's RV/100 is on the wrong side of things, Keller's worst off than Mears, which is surprising because the former's pitch is generally been held in higher regards than the latter.

Mears has been getting more swing and misses with the fastball, but when they do make contact they've been hitting him hard. His fastball compares similar to Mitch Keller's curveball (yikes) when looking at xwOBA.

Keller on the other hand, hasn't been missing bats with his fastball but has still been able to get outs with it.

While it's nice to miss bats at a higher rate, you still have to get the batters out in the end, and Keller has been better at that with his fastball.

Now looking at each player's curveball, and a lot of it speaks the same as the fastball but with more upside on Mear's end.


Curveball Metric






Whiff %



Strikeout %











Again he is missing a lot of bats with his curve, with a whiff rate at 40%. The difference is, when the hitters are making contact with the pitch, Mears is still getting outs. His expected batting average is even lower than than his actual mark, standing at .162. 

His xwOBA, which sits at .237, puts his curveball in the same category as JT Brubaker's curveball and Chase De Jong's change up (yes, statistically it was a good pitch) as some of the better pitches on the Pirates staff.

For Keller, his curveball, by ways of his xwOBA, compares to Chad Kuhl's slider which against is a fairly good comparison especially as of late.

What does it all mean?

So, yea, that was a lot of numbers I just threw at you, and if you are still with more through all of it, I applaud you especially given the topic.

While Mears and Keller aren't big pieces of the future, they do play a crucial part in the team's plans. We have seen first hand this year some of the struggles that the rotation has had getting deep into games, so that leaves a lot of clean up for the pitching bullpen.

If the starter only goes five innings and your working with the lead, that's six outs that's needed before you can turn the game over to the back of the bullpen - Chris Stratton and David Bednar. So that's going to fall on the likes of Keller and Mears to find a way to get those final six outs, and as we have seen that's been a battle at times.

While the current sample size that we have is too small to make a definite answer, I do believe there is still some upside with both pitchers, not as late inning options, but as members of the bullpen.

Keller's underlying numbers is a little more impressive but you can't argue with Mears' ability to miss bats with both of his pitches, especially in relief.

The most common term tossed out currently is 'evaluation period', a chance to look at what each individual player can bring to the table. 

Watching to see if Mears and Keller can learn to pitch to what some of the underlying numbers say about them is one of the more interesting evaluating points that I will be watching for the rest of the season.

You can follow me on Twitter, @__Murphy88. Also, subscribe to the site using the link at the top of the page.


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