Here's a guess.
At the moment, the Dodgers don't have much confidence in any of their relievers other than closer Kenley Jansen. In three postseason games, five Dodgers relievers have allowed six earned runs in just 6 1/3 innings. They've allowed a home run in each game.
From the beginning of this season, the Dodgers' bullpen has been an ongoing issue, as injuries and poor performances have forced Mattingly to rearrange roles.
So in the 3-1 loss of Game 3 of the National League Division Series against the Cardinals on Monday night, he did just that again.
In going for left-hander Scott Elbert to open the seventh inning of a 1-1 game, Mattingly was making a huge statement about the confidence he has in his other relievers.
And it didn't work. Elbert allowed a leadoff double to Yadier Molina, and one batter later, surrendered a two-run home run to Kolten Wong. In a blink of an eye, a 1-1 tie became a 3-1 deficit, and so the Dodgers will be facing an elimination contest in Game 4 today on FOX Sports 1 at 2 p.m. PT.
Later, in a quiet, resolute clubhouse, the Dodgers said the things they were supposed to say about their bullpen.
"It's the guys we've got," Dodgers catcher A.J. Ellis said. "It's guys who've done it before and gotten big outs in playoff games before. Trust what they're doing. Trust their stuff. There's really no time for huge adjustments. We'll go out tomorrow and compete."
So why Elbert?
His entire season in the big leagues consisted of seven September appearances. He was even designated for assignment at one point.
Was it fair to put him in this situation?
How about veteran left-hander J.P. Howell? How about Brandon League or Brian Wilson or anyone else?
"We haven't had a lot of success with our lefties, wanted to give them a different look," Mattingly said.
It was something of a surprise when Elbert was included on the Dodgers' postseason roster. One reason might have been how Howell struggled at times down the stretch. So with Molina and two left-hander hitters, Jon Jay and Wong, coming up, Mattingly went for his other left-handed option.
His explanation made sense, sort of. If the Dodgers' front office thought Elbert deserved to be on the roster, then why not use him?
To his credit, Elbert stood in front of his locker and faced waves of reporters after being charged with two earned runs in two-thirds of an inning.
He said he'd tried to get a pitch in on Wong's hands and left too much of it over the plate.
"He got the pitch he was looking for and didn't miss it," Elbert said.
Asked if he was surprised to be in the game at that point, he said, "You've got to be prepared for whatever's thrown at you. I'm just going out there trying to get guys out."
This was never the bullpen the Dodgers thought they'd have in October. The original blueprint was to have Chris Withrow, Wilson and Jansen lined up to pitch the seventh, eighth and ninth innings.
Things began to come undone early in the season when Withrow blew out his elbow. Wilson hasn't been as dominant as he was last year, so the entire season has been a scramble to find relievers.
Uncertainty in the bullpen probably is the reason the Dodgers included eight relievers, instead of seven, on their postseason roster. But as managers often say, when things are going badly, no number is large enough.
The Dodgers are learning that lesson the toughest way possible. Now facing an elimination game, Mattingly hopes Clayton Kershaw goes deep into the game today and that he can figure out how to get the ball into Jansen's hands.
The Dodgers' margin for error has run out. The experimenting probably hasn't.