At times, Uehara looking like mere mortal

It’s not an easy idea to grasp, this notion of Koji Uehara as a work in progress instead of ninja closer, one whose entry into a game last season meant everyone else could relax.

But even after a turn-back-the-clock night of Koji Time on Wednesday, one in which Uehara struck out the side on 10 pitches to preserve Boston’s 4-3 win over the Cincinnati Reds, the 39-year-old Red Sox pitcher acknowledged that he is still short of where he wants to be.

“Mechanics-wise, I don’t think I’m quite there,” Uehara said before the Sox departed for Texas and a three-game series against the Rangers that opens Friday. “The split, I wasn’t completely satisfied with how it was acting at all.”

This has not been an easy spring for Uehara. He has converted all eight of his save opportunities, but he was shut down for a few days last month with some shoulder stiffness, and since returning has endured some long innings -- it took him 27 pitches to get through the ninth inning Sunday against Oakland -- and was taken deep twice in the span of six days, first by Jose Bautista in Toronto, then with a ninth-inning, tie-breaking home run by Yunel Escobar of the Rays that pinned a loss on Uehara last Thursday.

Reds catcher Tucker Barnhart came close to duplicating Escobar’s feat Tuesday night, when he launched a ball deep to right in the ninth inning of a 3-3 tie. In Cincinnati, the ball would have landed 20 rows into the seats. In Fenway Park, it died in Shane Victorino’s glove a couple of feet in front of the fence.

Red Sox manager John Farrell brought Uehara back the next night, and was much more encouraged by what he saw.

“Much more sharp,” Farrell said after Wednesday's outing. “I know he’s been working on some things. The last few times out he’s been across himself with his direction and his delivery and it’s taken away from the crispness and the overall command of his stuff. He was able to get back on line a little bit here tonight, and he was Koji-like, [the way] we’ve seen for quite a while.”

Uehara insists that he is healthy, that he would not be pitching if he were hurt. But he admitted that his mechanics have been off, that he has been throwing across his body instead of going right at a hitter, and pointed to a physical reason for that being the case: advancing age.

“I think it’s more of some accumulated fatigue,” he said. “I’m not that young.”

There is also the matter of Uehara’s workload last season -- 74 1/3 innings in the regular season, an additional 13 2/3 high-leverage innings in the postseason. That’s more than double the 36 innings he had pitched in 2013 for Texas, and having worked deep into October, also made for a shorter recovery time in the offseason.

Red Sox GM Ben Cherington was motivated this winter to sign another experienced closer, Edward Mujica, in part by his concerns about how Uehara would bounce back.

Uehara said he has been trying to build additional arm strength through long toss and playing catch, and said he had similar issues this time last year. But arm fatigue often can leave a pitcher more vulnerable to injury, and while Farrell insists that Uehara has recovered fully from the shoulder stiffness that plagued him earlier, it still bears watching.

After striking out 17 of the first 39 batters he faced this season, Uehara had fanned just two of 17 batters until whiffing the side Wednesday.

According to Fangraphs.com, the velocity on both of Uehara’s pitches, his fastball and splitter, is down from last season. He’s averaging just 87.7 mph on his fastball, compared to 89.2 in 2013, and the splitter is down to 79.4 mph compared to 81 in 2013.

His strikeout rate is down, from 38.1 percent to 37.3 percent, while his walk rate is up, from 3.4 percent to 5.1 percent. Opponents, who batted .129 against him last season, are hitting .232, and his batting average on balls in play (BABIP) has risen from .188 to .344.

Perhaps indicative of the issues he has had with his splitter (“I was elevating”) is that his ground-ball percentage is down substantially, from 40.4 percent to 31.3 percent, while his line-drive percentage has risen from 11.3 percent to 15.6 percent.

Still, Uehara’s perceived “problems” might not even register as such if he had not set the bar so high in 2013. He acknowledged as much when asked how close he is to where he wants to be.

“One season,” he said.

ESPN Boston contributor Kyle Brasseur contributed to this report.