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The battle for the 5th spot in the Cubs rotation has begun

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Mills, Chatwood and Alzolay will get the Cubs first three spring starts

Adbert Alzolay pitches at Pittsburgh in July
Photo by Mark Alberti/Icon Sportswire via Getty Images

At Cubs Convention there were a few questions that came up repeatedly: Will Kris Bryant be traded? (Apparently, no). Who will bat lead off? (Apparently, Kris Bryant). One of the things fans speculated about the most was who would fill the fifth spot in the starting rotation vacated by Cole Hamels and who would wind up in Iowa or the bullpen.

Well, we don’t have an answer to that final question, but per ESPN’s Jesse Rogers, it looks like the Cubs aren’t wasting any time gathering data to figure out an answer:

The three most likely pitchers to compete for the fifth spot in the rotation will start the Cubs first spring training games, so I wanted to take a quick look at their body of work from 2019. Before that, however, a quick caveat: players frequently use spring training games to work out a game plan or try something new. As a result, spring training stats just don’t tell us all that much about what a player will do in the regular season. So this is less about actual results and more about looking at these pitchers more generally. Here’s what I’ll be keeping an eye on for these three potential starters.

Alec Mills

Most people (and projection systems) seem to think that the fifth spot is likely going to Tyler Chatwood. I made the case in December that it should go to Alec Mills, and I still stand by that:

Mills isn’t a power arm, but he has good stuff and his K/9 of 10.5 was second only to Yu Darvish among Cubs starters last year and given the lack of moves the Cubs have made this offseason I imagine we’ll see him every fifth day at the start of the 2020 season.

According to Brooks Baseball - Mills throws a 90 mile per hour four-seam fastball about 35 percent of the time. He mixes that with a 90 mile per hour sinker, a change up and a curve ball. As a starer for the Cubs in 2019 he threw 20 innings with an ERA of 2.70 and a K/9 of 11.7. His FIP of 3.56 as a starter indicates he got a little bit lucky in those starts, but I think the Cubs would happily take a 3.56 ERA every fifth day in 2020.

Tyler Chatwood

I’m so incredibly intrigued by Tyler Chatwood’s stuff. About a month ago someone I follow on Twitter posted a screenshot of his Statcast profile (I cannot for the life of me remember who that was or find the tweet, so I apologize for not giving them credit) and honestly just look at this:

Chatwood MLB rankings 2019
Statcast

Chatwood has elite spin rate on his fastball and curve. His fastball spin rate is in the 95th percentile of the league, his curve is in the 99th. The stuff isn’t just good - it's great - when he can control it. And therein lies the question, because while 2019 Chatwood was orders of magnitude better than 2018 Chatwood, 2019 Chatwood was also better by almost every metric out of the bullpen than starting. The differences are big enough that I wonder if he’d be better with an opener. See for yourself below:

Tyler Chatwood splits 2019

IP BB/9 K/9 ERA FIP
IP BB/9 K/9 ERA FIP
22.2 4.76 8.34 3.97 4.49
54.0 4.17 8.83 3.67 4.20
Select stats Tyler Chatwood as starter/reliever Fangraphs

Adbert Alzolay

Alzolay has the highest upside of these three options. He’s four years younger than Alec Mills and showed signs of brilliance when he first came up with the Cubs in 2020. I mean, who can forget this debut [VIDEO].

But shortly after this exceptional debut he was shelled in back to back outings. And then he was hurt, like he has been so many times in his young career. Alzolay relies on three pitches and while we don’t have enough Statcast data to know where he sits relative to the rest of MLB, his fastball and curve are both top rated pitches according to scouts. I worry a bit that he needs a fourth pitch if he’s going to be a starting caliber pitcher long term:

Alzolay pitch type and location
Statcast

Takeaways

This is part of why my hashtag for the 2020 Cubs is #HighUpside. Any one of these pitchers could exceed expectations and be more than an adequate fifth starter. Any one of these pitchers could also be a total bust. I’ll be watching all three of them closely as spring training games start Saturday.