BOSTON — Maybe Coco Crisp could have hauled in Adam Kennedy’s long drive off the base of the center-field wall with two out in the ninth if he hadn’t taken a step in first before retreating. Maybe not.

But relief pitchers lay awake at night, unable to sleep, when they get beaten on anything but their best pitch.

And that fat splitter that Jonathan Papelbon served up to Kennedy, a pinch-hit double that delivered the blown-save tying run on an 0-and-2 count, did not come on Papelbon’s best pitch. Not yesterday, anyway.

Papelbon entered the game trying to nail down a come-from-behind 3-2 win. He punched out Rick Ankiel on three pitches, all fastballs, the last of which blazed to the plate at 97 mph. He followed that up with another three-pitch whiff, this one of Yadier Molina, again on a 97-mph fastball.

So it was two up, two down, on six pitches, all fastballs.

Next was Chris Duncan, a pinch hitter.

Papelbon elected to mix in a splitter. Not even close. No bite to it. Ball one. He tried another one. Again, there was no sharpness to it. Ball two. He tried to get back into the count but his next two pitches — fastballs — missed. That walk sent Duncan to first base.

When Kennedy stepped in, Papelbon went back to his fastball. Kennedy swung and missed the first one, a 96-mph heater. Papelbon pumped in three more fastballs, each one at 97. Kennedy fouled each one back.

Papelbon and catcher Jason Varitek tried to put Kennedy away with a splitter, figuring he was on the fastball. On this day, though, Papelbon’s splitter wasn’t good.

He fired it to the plate at 91 mph. It was over the heart of the plate. It had no downward movement — until it neared the center-field fence and scored Duncan, who was running on the pitch. That tied the game at 3-3.

It was Papelbon’s fourth blown save of the year and second in his last four chances. Papelbon gave up a save in Cincinnati eight days earlier — on a splitter that the Reds’ Edwin Encarnacion hit for a solo homer with two outs and no one on.

The count had gone to 2-and-2 on Encarnacion. Papelbon tried two fastballs and Encarnacion fouled them off, so Papelbon tried the splitter. That one had very little downward action — until it sank into the left-field seats.

skrasne@projo.com