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The early returns on the six-man rotation are positive

In lieu of adding a bona fide ace at the trade deadline, the Orioles have decided to go with quantity over quality. So far… it’s looking pretty good.

Toronto Blue Jays v Baltimore Orioles
Kyle Gibson and Jack Flaherty sharing a laugh during a game against Toronto on August 24.
Photo by Jess Rapfogel/Getty Images

It’s hard to remember a season where the starting rotation wasn’t an area of prime concern for the Orioles and, despite this team’s stunning success, 2023 hasn’t turned out to be that different. As a unit, their 4.31 ERA/4.31 FIP is exactly average—not a drag, but the starters are certainly not the reason the O’s are shocking the baseball world by leading the AL in wins right now.

The Orioles have gotten real contributions from the Kyles (Gibson and Bradish), half a brilliant season from Tyler Wells, and a really nice recent run from Dean Kremer. But there’s been lots of instability all year: the early demotions of No. 2 prospect Grayson Rodriguez and veteran Cole Irvin; Tyler Wells’ stuff dropping off a cliff in July from fatigue; John Means’ return from Tommy John being pushed back twice; Jack Flaherty’s 6.41 ERA since becoming an Oriole.

Length has been a problem for the rotation all season, and as you’ve probably heard, several of the Orioles’ young starters have already blown past their personal career highs in innings with a month still left in the season: Kremer (already +25 IP), Bradish (+16 IP), Wells (+10 IP) and of course, the rookie Rodriguez.

So perhaps it wasn’t a head-scratcher when, on August 11, the Orioles announced that they were moving to an expanded six-man rotation by promoting Irvin from a swingman role and reinserting him into the rotation.

Two weeks in, the experiment has already been pronounced a success. The starters have a combined 3.30 ERA and 1.047 WHIP in that stretch, including a shocking 2.81 ERA in three starts for Cole Irvin! That’s great, and massive for the Orioles to build trust in their starters (slash a possible swingman) as they aim for the postseason.

On the other hand, the six-man rotation surely hasn’t ironed out all of Baltimore’s pitching problems. Questions can be asked about whether we’re crediting the wrong thing for recent improvements, or overlooking its potential flaws. Here are three.

1. The “Correlation ≠ Causation” Problem

The flashiest number associated with the Aug. 11 rollout is a brilliant 1.96 combined ERA between Kremer, Rodriguez and Bradish in nine starts. But weren’t these young starters already improving without a six-man rotation? Are the extra days making a difference?

Quick answer: the pitchers themselves say “yes,” and the data, while limited, appears to back them up. Obviously, Grayson Rodriguez’s month of work at Norfolk on mechanical tweaks is the real difference-maker between his 7.35 ERA in the first half and 2.83 ERA since. But his last two weeks have actually been his best all year (2.24 ERA, 6 IP per start). And there does seem to be a slight correlation between days rest and his outcomes—not to mention, as The Sun pointed out, that he’s flashed his highest average fastball velo in his past six appearances. Bradish? Same. Despite already being on an upward trend, with a 2.23 ERA in his past 13 starts, his last two weeks have also been his best all year. Kremer? A sparkling 2.00 ERA in three starts averaging six innings a pop, also his best three-outing stretch of the season.

Granted, I didn’t run regressions to control for quality of competition and thing like that, but since the O’s recent opponents have included Seattle, San Diego and Toronto, this seems unlikely to be driving everything. Pretty cool: despite this being the “dog days” of the season, the O’s youngsters seem to be feeling refreshed.

2. The “Too Many Cooks” Problem

Is it better to have more starters taking turns in the rotation, if some of them are bad? Consider that Kyle Gibson and Jack Flaherty are not looking good recently. Would you rather have one of them every six days or a less-rested Dean Kremer every five?

Here, it’s soon to say. Someone cleverer than me could probably frame this as an equation and calculate the net swing. But one indication that this is the right move, despite more of the back of the rotation, is that, for Flaherty at least, rest has made a big difference this year. His stats aren’t linear (they actually go “medium, worst, best” with 4, 5, and 6 days of rest, respectively) but more rest clearly produces better numbers out of him. Through five starts under these conditions, Flaherty has a 2.20 ERA, 1.15 WHIP and opposing average/OPS of .180/.582. He’s had longevity problems over the last four seasons, but is also quite talented, so why not see if extended rest might make a difference?

(Note, though, that the trend is not as clear-cut with Gibson and Irvin, who both seem to like working on five but not six days’ rest, and it doesn’t hold for Flare over the length of his career, just 2023.)

3. The “Robbing Peter to Pay Paul” Problem

One of Buck Showalter’s favorite expressions while he still managed this team, this one was used to rule out drastic changes that risk having adverse effects down the line. Current manager Brandon Hyde doesn’t have the same folksy sayings, but we know he spotted the same potential problem: would the six-man rotation cause havoc in a bullpen now reduced to seven arms—especially now that All-Star closer Félix Bautista may be out for the season with an elbow?

Again, so far there’s reason to think the starters are making up the difference. As The Sun points out, the O’s starter has gone six innings in 11 of the past 17 games. Other than Gibson, who’s regressed, and Flaherty, who wasn’t an Oriole before and whose health is still a question mark, all the starters are averaging longer starts in August than they were, say, in May or July. This is a huge turnaround.

Nor has the bullpen regressed much. In fact, key pieces like Cionel Pérez are finally locking into form (he has a 0.00 ERA in his last seven appearances), and Yennier Cano is finding his early dominance, too (0.00 ERA in his last nine). Danny Coulombe is back from injury, and new guy Jacob Webb is also doing enough to be very interesting. Perhaps the takeaway is that bullpen membership is variable enough that, in a deep organization like this one, when one guy stumbles, another can be slotted in without too much damage to the group. Now add in DL Hall, who’s looked great in two outings, and hopefully John Means and Tyler Wells down the stretch. I think “Peter” seems to be doing just fine.

Despite a little devil’s argumentation here, the six-man rotation is seeming to stand up to scrutiny, a clever strategic tweak by the Orioles, especially for a pitching staff configured like this one.

Good timing. As Brandon Hyde says, “We’re planning on playing an extra month, and to do that, we’ve got to get there first.”