Koji Uehara, Craig Kimbrel at a loss to explain eighth-inning meltdown

BOSTON -- They are the Red Sox's K-Men -- Koji and Kimbrel, the former closer and the current one -- and together, they usually can be counted on to safeguard even the slimmest of late-inning leads.

But they aren't infallible. And with their twin collapses in Monday's 4-3 Patriots' Day matinee loss to the Toronto Blue Jays -- and their ensuing inability to explain what happened -- they also raised a couple of potential red flags.

Let's start with Koji Uehara, who laughed off questions about why he was seen shaking his right hand in between pitches during a five-batter sequence in which he gave up an infield single, walked two batters and hit another.

"That was nothing," the 41-year-old right-hander said through translator C.J. Matsumoto before joking, "It's probably just early morning. It was just my body was not awake."

OK, so maybe Uehara really isn't a morning person. He did, after all, post a 5.06 ERA in day games last season. But when you consider, too, that he shied away from throwing his signature splitter in favor of his fastball, it's worth asking again whether he was dealing with anything physical on the mound, especially after a line drive broke his wrist and ended his season last August.

"It was just what Vazqui [catcher Christian Vazquez] was putting down," Uehara said of his pitch selection. "Nothing on my part."

Added manager John Farrell: "From time to time, he'll loosen up the wrist. Nothing bothering him physically. Uncharacteristic loss of [the] command that we've been so accustomed to seeing."

Uehara, who inherited a 1-0 lead from starter Clay Buchholz and reliever Junichi Tazawa, gave up the tying run on an RBI groundout by Michael Saunders, then hit Josh Donaldson and walked Jose Bautista to load the bases.

At that point, Farrell called on Craig Kimbrel, whose 16.66 strikeouts per nine innings since 2011 rank second among all major league pitchers with at least 50 innings pitched, trailing only suspended New York Yankees closer Aroldis Chapman. Kimbrel had been dominant since blowing a save in the home opener at Fenway Park on April 11, striking out eight of the past nine batters he faced entering Monday.

Sure enough, Kimbrel fanned the dangerous Edwin Encarnacion and was one strike away from finishing Troy Tulowitzki. That's when he abruptly lost his command, nearly hitting the Blue Jays shortstop with ball four and walking in a run for the first time in his career.

"They were balls," Kimbrel bristled when asked what happened on the final three pitches to Tulowitzki. "He didn't swing at them. When you throw the ball and it's not over the plate, it's a ball. So, that's it."

Fine. But while Kimbrel isn't some strike-throwing robot, he also has issued only 2.9 walks per nine innings over the past four seasons with the Atlanta Braves and San Diego Padres. He has walked five batters in 6 2/3 innings thus far this season.

Kimbrel didn't offer any of the ready-made excuses about entering in the eighth inning rather than the ninth, rushing to get loose or coming into a non-save situation. But he also couldn't explain why he suddenly needed a GPS to find the strike zone.

"Being ahead of Tulowitzki and having a real good chance," Kimbrel said, "walking him right there wasn't really what we had written up."

After Kimbrel's blown save one week earlier against the Baltimore Orioles, pitching coach Carl Willis suggested he was overthrowing in his first save attempt at Fenway since being acquired for four prospects in a November trade with the Padres. That wasn't the case this time, according to Farrell.

"He's trying to throw pitches to the edge and not so much where he's just looking to go middle-middle," Farrell said. "We're ahead, 1-2 count with Tulowitzki, that was the at-bat right there. I can't say there was overthrowing going on there to try to put him away, but we let him back in the count."

Of course, Farrell isn't about to stop trusting Uehara or Kimbrel with leads, and based on their track records, he shouldn't. Uehara, though, might benefit from pitching less often. He has appeared in eight of the Sox's 12 games, a product of fellow setup man Carson Smith beginning the season on the disabled list with a forearm strain and perhaps Farrell's lack of faith in young right-handers Matt Barnes and Noe Ramirez.

"We've got roles established, and that's where the seventh, eighth and ninth have been efficient," Farrell said. "They've been successful. This is, I think, a little bit of a blip with Koji today. That bullpen group knows that they're there to pick one another up in certain situations, but the highest-leverage inning clearly was the eighth. Hopefully we don't find ourselves in that spot too often."

In the end, maybe this was merely an outlier for Koji and Kimbrel. But they faltered badly enough Monday to spark some concern.