As Craig Kimbrel focuses on his infant daughter, Red Sox contemplate ninth inning options

FORT MYERS, Fla. -- As if the uncertainty surrounding the back end of their starting rotation – with the availability of three projected starters unknown for the start of a season less than two weeks away – wasn’t enough for the Red Sox, there’s now the same unknown associated with their closer.

Craig Kimbrel has been absent from camp for several weeks now, as his infant daughter, Lydia, underwent a second surgical procedure on her heart back in Boston. By most indications, Lydia is improving daily – “Things are getting better…still getting better,’’ reported Alex Cora on Friday – but there’s still no assurance that Kimbrel will return to camp in time to be ready for the March 29 opener at Tropicana Field.

Kimbrel has continued to throw back in Boston, and found some hitters to whom he threw live batting practice Thursday.

“I talked to one of our trainers,’’ said Cora, “and he feels he’s actually in a better place  - as far his strength and his arm – than previous years. So that’s a good sign.’’

But there’s obviously a huge difference between throwing in a controlled setting in an indoor cage in Boston, and facing major league hitters in Florida. No matter how hard Kimbrel is working to build and maintain arm strength, it would seem implausible for him to parachute in in the final week of spring training and be ready to protect a one-run lead days later.

“We’re still waiting,’’ said Cora. “Obviously, it’s about Lydia and if she keeps improving, they’ll make a decision as a family and whatever they decide, we’ll agree. We’ll see. If he has to stay up there, he stays; if he comes down, he comes down.’’

Cora has some options to close in Kimbrel’s absence. Carson Smith, whose stuff has looked exceptional this spring, had 13 saves in 2015 while with the Seattle Mariners and would likely be looked upon as the first option should Kimbrel not be available.

Matt Barnes has swing-and-miss capability and would be another the Sox could plug into the ninth inning early in the season. There likely would be enough trust in Joe Kelly, too.

Just as Cora plans to use the aforementioned trio as part of a group of relievers who could alternate set-up duties, depending on matchups, he could apply the same formula an inning later in the ninth.

Still, none of the options is as reliable as Kimbrel, who was the most effective and dominant closer in the American League last season, striking out almost exactly half the hitters he faced while allowing just 33 hitters in 69 innings and posting a 1.43 ERA and a microscopic WHIP of 0.68.

Cora has continuously preached that the Sox won’t take any shortcuts with pitchers’ health in the first week or two of the season, and while Kimbrel isn’t physically limited, he falls into the same category.

And his potential absence at the start of the season is one more reminder that the team you see on March 29 may be quite different from the one the Sox field several weeks later.