Analyzing the Giants’ pitching

Through nine games, the Giants have faced three teams: the Miami Marlins, the San Diego Padres, and the Cleveland Guardians. They’ve only lost two games, winning both the Marlins and Padres series and sweeping the Guardians. While their team offense ranks 18th in baseball, with exactly a 100 wRC+ (meaning exactly average), their starting pitching has been elite in every sense of the word, carrying the team out to their hot start.

The Giants lead the league in SP (starting pitching) WAR (1.7), FIP (1.62), K/9 (11.47), and are tied for first in xFIP (2.63) with the Mets. They’re fifth in SP ERA (2.47), but that might be because they’re ninth-highest in BABIP (.324), reflecting the fact that some of their pitchers are probably getting a bit unlucky. They’re second in the league in SP SIERA (2.45), behind the Mets (2.40). SIERA (Skill-interactive ERA) attempts to measure only the factors a pitcher can control, and includes type of contact (hard, soft, etc.). By every metric, advanced and basic, eye-test and data-driven, the Giants pitchers are good.

But how good? They’re the second team since 1901 to have their starters allow two runs or fewer in a nine-game stretch to open the season. They set a Giants franchise record for any nine-game stretch where the starters allow two runs or fewer.

And the Giants are a franchise with many great pitchers in their wheelhouse: Christy Mathewson, Juan Marichal, Gaylord Perry, just to name a few. So what’s making this iteration different?

The short answer is depth. The ceiling of every single one of their starting five is at least a capable #3 pitcher, if not more. Here are the best seasons for each starter:

2021 Logan Webb: 11-3, 3.03 ERA, 2.72 FIP, 3.13 SIERA, 4.1 fWAR

2021 Carlos Rodón: 13-5, 2.37 ERA, 2.65 FIP, 2.96 SIERA, 4.9 fWAR

2021 Anthony DeSclafani: 13-7, 3.17 ERA, 3.62 FIP, 4.11 SIERA, 3.0 fWAR

2017 Alex Wood: 16-3, 2.72 ERA, 3.32 FIP, 3.57 SIERA, 3.1 fWAR

2021 Alex Cobb: 8-3, 3.76 ERA, 2.92 FIP, 3.83 SIERA, 2.5 fWAR

Given all their ceilings, that would be a rotation with an overall WAR of 17.6. That would have been eighth in baseball in 2021. It’s not their staff is filled with an army of prime Clayton Kershaws, but rather that they have almost no pitchers that actively harm the Giants. And most of that rotation has seen recent success: the only non-2021 best season on there is Alex Wood’s, which only barely edged out his 2021 2.5 fWAR season.

Reasons for Optimism

So how is the starting pitching doing this? The obvious answer is obvious: they’re limiting runs. But the manner in which they’re doing it gives some hope that this may be something maintainable: they rank first in baseball in starter K/9 at 11.54, and they’re fifth in baseball for best BB/9 at just 1.85. Basically, they’re striking guys out and they’re not walking them; guys are having to earn their way on base, and when there are players on base, pitchers have kill pitches and out pitches that give them success against dangerous hitters. They also somehow lead the league in average fastball velocity (96.1 mph), despite none of their starters being Jacob deGrom/Hunter Greene types. Their WHIP ranks sixth in baseball (1.06) despite that aforementioned .324 BABIP, so it’s not just luck keeping men off the bases.

Using the Fangraphs “+ stats” page, we can compare more granular stats to league average. So, with the + stats, they are normalized against the league average so that a 150+ means a certain stat is 50% better than league average. The Giants are 151% better than league average on K/BB rate (251 K/BB+), a truly incredible mark, while being 12% worse than league average on BABIP (hence unlucky), as well as 7% worse than league average on LOB %.

Reasons for Pessimism

Their HR/FB is an ungodly 2.5%, and that will almost certainly regress. The league average HR/FB rate is usually just below 10%. They do rank 24th in baseball for % of hard contact allowed (lower is better) at 33.0%.

Their bullpen has been much more pedestrian: although the Giants are fourth in the league in reliever ERA (2.15), their FIP ranks 16th (3.85) and their xFIP 25th (4.27). You know this: you’ve seen the last couple of torturous ninth innings that the Giants manage to squeak out of by the skin of their teeth. That doesn’t make the prediction systems all that confident, even if the results on the field look great. However, the Giants have capable relievers in their ‘pen; it’s just a matter of getting adjusted. The Giants are 27% worse than league average when it comes to reliever K/9 and 20% worse than league average for reliever BB/9: their relievers have had trouble striking out players as well as keeping them off the base paths.

Summary

Nine games into the season, the Giants have amassed a truly wonderful starting rotation. In these very early days, Logan Webb and Carlos Ródon look as formidable a 1-2 punch as any in the big leagues, and the back end of the rotation has been filled out nicely by capable pitchers. There are reasons to assume some regression—a starter is going to give up more than two runs eventually—but the Giants look poised for success. Their rotation was a huge part of their historic franchise record 107 win season last year, and this iteration of the rotation might be even better: Gausman replaced by Rodón and Johnny Cueto with Alex Cobb.

The bullpen has been a little shakier to begin the year: while they’ve been getting results, it hasn’t been in a manner that has kept Giants fans particularly calm. Still, flashes from Tyler Beede and Sam Long suggest there may be long-term options there, and there are still young pitchers in the system that have the chance to come up and really prove themselves.

It’s been a fun ride watching the starting rotation over the first nine games (and nail-biting to watch how the 7th, 8th, and 9th innings sometimes play out). There’ll be a lot more of that this season, but for now, they’ve gotten off to as good of a start as anyone could expect.