What is a dominant start?
It’s a thought that crossed my mind earlier in the week, after some discussion about Mitch Keller and JT Brubaker over the weekend. I casually threw out the word “dominant” to describe the pair combining for two earned runs in over ten innings of work.
This led to one of my favorite or most annoying activity on the site (depending on the day): Word semantics.
After seeing a brief discussion about what constituted a “dominant” outing by a starter, I decided to look at some numbers.
The main argument against Keller and Brubaker not being dominant was that they didn’t pitch deep enough into the game. This is where my definition of “dominant” comes into play. I think there is very little that Keller or Brubaker can do to pitch deep into the game at this point in the season. They’re young pitchers, key to the future on a losing team, and neither has built up much of a workload this season.
Thus, if we’re saying that Keller and Brubaker can only be dominant if they go more than 5-plus innings, then I don’t think either pitcher has a realistic chance to be dominant on this team, this early.
I wanted to first see just how many pitchers go beyond 4-5 innings in today’s game. I looked at the numbers for all teams from 2019-2020 combined, trying to get a recent look.
Pitching Deep Into the Game
Here is how often MLB pitchers reached an inning total in a game during 2019-20.
4+ IP: 85.8%
5+ IP: 68.7%
6+ IP: 40.3%
7+ IP: 14.6%
8+ IP: 2.6%
Most games saw pitchers going 4+ innings, and almost 70% saw one pitcher throwing five or more innings. There’s a big drop around the seven inning mark, with less than 15% of games seeing a pitcher go seven or more innings.
Keep in mind, this is only tracking pitching deep. It doesn’t take into account how the pitcher performs, which is the other side of this coin.
Limiting Damage While Pitching Deep
So, what is a dominant start?
The average ERA in 2019-20 was around 4.50, which is a perfectly round number for evaluating expected performances from pitchers.
We’d expect a dominant pitcher to perform better than the average, which would be two runs in four innings, three in six, or four in eight.
For the purposes of this study, I considered dominant anything with one or fewer runs in less than six innings; two or fewer runs in less than eight innings; three or fewer runs in eight or more innings. Here is how the numbers broke down:
4-5.9 IP, 1 ER max: 11.8%
6-7.9 IP, 2 ER max: 26.7%
8+ IP, 3 ER max: 2.6%
That’s a combined average of about 41% of starts being considered dominant, which is probably too high. That number would come down if you use an innings limit and remove the 4-5.9 IP group. You’d have less than a third of your starts as dominant, which seems to be more in line with expectations for the word.
Let’s go a little more extreme.
How about 4-5.9 shutout innings, 6-7.9 innings with 1 ER max, and 8+ innings with 2 ER max:
4-5.9 IP, 0 ER: 4.3%
6-7.9 IP, 1 ER max: 17.9%
8+ IP, 2 ER max: 2.5%
That seems more like a consensus version of “dominant”.
Of course, then what would we then use to describe elite?
Expectations For a Starter
The interesting thing about that 4-5 inning group above is that anyone would take those results. Pair them with the right reliever, and you’ve got a dominant starter in the aggregate. And you kind of wonder what the circumstances were that limited all of those pitchers in innings when they were doing well in limiting damage.
Most of the gams from 2019-20 saw a pitcher go 4-6 innings. Less than 15% of pitchers went seven or more innings. However, most of those outings were probably considered dominant to allow the pitcher to go so deep.
If I was coming up with a sliding scale, I’d say a dominant start would be:
5-6 IP, 1 ER
7+ IP, 2 ER
I’d also take every single 4 IP, 1 ER outing I could get, and would pair that outing with a long-reliever, hoping to get a dominant start in the aggregate.
All of this is very subjective, and I think any of us would take any outcome with low run totals attached. This does give some insight as to what to expect from pitchers, and how to evaluate their performances.
Regardless, I still intend to use words that are subjective but feel objective, and highlight them in such a way that it will detract from the thousand other words in the article.