As noted in Sunday’s column, Koji Uehara has thrown 24 pitches this season, and 21 of them have been splitters. Even for a two-game sample, that’s pretty extreme. Only one other pitcher – Red Sox teammate Edward Mujica (57.6%) – has thrown a splitter with more than 50% frequency in the early going. Last year’s leader was Chicago’s Zach Putnam, at 56.1%, while Uehara was right behind him at 47.5%.

The Boston closer has fanned four of the six batters he’s faced, so you can’t argue with the results. But it’s hard not to wonder where his fastball is, and whether he trusts it right now. Uehara is 40 years old and began the season on the disabled list due to a hamstring injury.

Pitching coach Juan Nieves told me Uehara is healthy and has “one of the best fastballs in the league; an invisible fastball.” He said he’s fine with that many splitters, and if Uehara “keeps putting up zeroes, he can use it as much as he wants.”

I asked Ryan Hanigan, who was behind the plate for both appearances, if he’s ever called such a high percentage of a particular breaking pitch. He said he hadn’t. I also asked if throwing almost exclusively splitters was the plan going into each of Uehara’s outings. He told me it wasn’t.

Uehara won’t continue to throw 87.5% splitters, but he’ll certainly feature it in the months to come. According to his catcher, it’s not only effective, it’s more than one pitch.

“He can throw it for a strike and he can throw more of an action pitch to get more sink,” said Hanigan. “He can play with it and let it run a little bit. He can do different things with it, at different speeds, and he’s got real good command of it. There will be times we’ll go with the heater more often, but I’ll call the splitter at any time.”