Detroit Tigers: What makes a pitcher an ace in 2021?

If there is one thing I appreciate about baseball, it’s how you can identify the winds of change based on numbers. For example, let’s go back to 1971 and look at the Detroit Tigers’ starting rotation.

This is three seasons after the “Year of the Pitcher” in 1968 in which the mound was lowered from 15 inches to 10 to give the batters a fighting chance. It is crazy to think manager Billy Martin ran a three-man rotation, but he really had no choice. Dean Chance, Joe Niekro, and Mike Kilkenny were the only other pitchers who started at least 10 games that season. Bullpen arms started becoming more of a weapon later in the ’70s.

To put this into perspective, Matthew Boyd and Spencer Turnbull, the two starters who threw the most innings for the Detroit Tigers in 2019, combined for 333 IP. No Tigers pitcher has topped 300 innings in a season since Lolich did it in 1974. Only one Tigers pitcher has gone over 250 innings since 1987 (Justin Verlander in 2011), and since Verlander left in 2017,  Boyd is the only Tigers pitcher to top 180 innings in a season.

So why am I bringing this up? In the MCB Slack chat Chris Brown mentioned the idea of the pitching ace baseline (or “aceline”) continuing to evolve, with starters being asked to throw fewer innings than ever. So I thought it would be interesting to look at what that new ace baseline could be for the Detroit Tigers in 2021 and beyond.

The Standards Have Changed

The days of pitchers winning 300 games are over. When pitcher enters the Hall of Fame in the future, their cases will be based on a newer set of criteria. The unusual 2020 season changed the course of stats for pitchers, with far fewer games and some  7-inning affairs. Teams are making bullpen starts more frequently now, and the Tigers joined adopted this practice more willingly than they did with the last big pitching trend, the five-man rotation.

The talk about bringing back four-man rotations came up last season due to the shortened season. The practice is not common anymore, and the last manager to use the four-man rotation was Earl Weaver for the Baltimore Orioles.  Sparky Anderson spoke very highly of Earl Weaver in an interview with the Chicago Tribune in 1998 and why he thought Weaver was smarter than anyone else when it came to using a four-man rotation.

"“He had his best four pitchers pitching every fourth day. He realized his fifth best was the worst of the lot. So why run him out there? When I began managing I tried it one year, for a short while, maybe twice around. I don’t know why but we convinced ourselves that these young people needed a rest. I always thought it was the old people who need a rest.”"

He even showed some regret about how he used his rotations.

"“I’m not a pitching coach,” Anderson said. “But I know this, looking back on my 26 years, I was absolutely wrong. If I had pitched four guys and used them with three days of rest, every fourth day, they would have been better pitchers. It’s too late for me, but I want to admit I was wrong.”"

Outside of the quick history lesson, I brought up the rotation angle because in 2021 we might see teams going as deep as eight to nine starters who could average five or more starts. And as a result,  what we perceive as an ace could change fairly drastically.

Detroit Tigers Past Aces

Let’s take a look at the past three decades and find the five best seasons Tigers aces had each decade, ranked by WAR. As a point of reference, if you are not familiar with how WAR is broken down, here’s how it works based on the chart created by FanGraphs.

6+ MVP
5-6 Superstar
4-5 All-Star
3-4 Good Player
2-3 Solid Starter
1-2 Role Player
0-1 Scrub

Quality starts (QS) are starts in which pitcher goes six or more innings and allows three or fewer runs.

1970 to 1980

Fidyrch’s season is just unreal — 29 starts, 23 quality starts, and 24 complete games. Keep in mind in how different of an era that was. He produced that WAR with just a K rate of 9.7%.

1980 to 1990

*Doyle Alexander threw 206 innings between Atlanta & Detroit in 1987.

For the 1990s,  Justin Thompson’s 1997 season was the 10th best season in Tigers history with a 7.7 WAR. He started 32 games, threw 25 quality starts, and went 15-11.  I will skip this decade though, because outside of that season, Detroit’s starting pitching was not very good. Among the top five in WAR, only Thompson and Brian Moehler threw 200 innings in a season and were considered in the All-Star category by WAR.

2000 to 2020

So now you have a brief history of the “aces” of the Detroit Tigers of the past several decades in terms of best WARs throughout the decade.

Educated Guess

You probably noticed that apart from the ’90s, the Tigers have had some impressive pitching performances. But each decade brought a drop in the total number of innings pitched as velocity, arm injuries, and bullpen usage all increased.

Another trend I noticed for the higher WARs on the Tigers list was that anyone who threw at least 150 innings and produced 4+ WAR also managed at least 15 quality starts.

From 2017 to 2019 there were exactly 100 instances in which an MLB starter threw 180 innings or more in a season. If we look at the top 30 FIP leaders from that window we see 29 pitchers with at least 4 WAR and 23 with at least 5 WAR. Accumulating 5 WAR makes you an All-Star and generally the “ace” in any pitching staff.

So this brings us back to the Tigers pitchers in 2021, who look as though they’ll begin the new decade by having to cover a full 162 game schedule.  AJ Hinch has said Detroit may go to a six-man rotation this season, with Daniel Norris or Tyler Alexander coming out of the bullpen to start.

Since 2017, if you take out Justin Verlander from the chart below, here’s how it breaks down with at least 150 innings min, the Tigers recent pitching performances.

We may never see 200 innings in a season again, so if we are going to establish an “ace line” for the Tigers, Detroit will need at least 170 innings pitched and 15 or more quality starts from their ace this season.

Casey Mize and Tarik Skubal have never thrown 125 innings in a season, and even in Michael Fulmer’s Rookie of the Year season he threw just 159 innings, though he did manage 15 quality starts and 5.4 WAR. It’s possible Mize, Skubal, and Matt Manning may get to ace level eventually, but it probably won’t be in 2021.

For those exciting young arms to get a chance to reach their ceiling, Detroit will need to address the rotation with another veteran starter who can buy them more time by eating innings in 2021. Otherwise the Detroit Tigers may go another decade without a true ace.