PHOENIX -- Perhaps the pitchers are not holding the runners on well enough.
Or maybe the catchers are not throwing the ball quickly enough.
Then again it could be, as manager Kirk Gibson mentioned, simply a matter of circumstance; just look at who they've played.
Whatever the reason, the problem remains the same: Opponents are much too successful stealing bases.
Entering play Monday, the Diamondbacks had allowed 24 stolen bases, which ranked second-worst -- tied with the Pirates -- in all of baseball.
"We've done a really good job of it in the past, but we haven't been as fortunate this year," Gibson said ahead of the series opener against the Rockies Monday. "Miggy (Miguel Montero) probably hasn't thrown the ball as good as he has in the past, but he goes out and he works on it almost daily."
Montero has thrown out only one would-be base stealer in 18 attempts. He and backup Tuffy Gosewisch are a combined 1-for-25 this season.
Of the 24 bases swiped, 11 can be credited to the game's top stolen base threats: Dee Gordon (5, including four on April 13) of the Dodgers, Eric Young, Jr. (3) of the Mets and Ben Revere (3) of the Phillies.
Gordon leads the majors with 13 stolen bases. Young (12) is second and Revere (9) is tied for third.
"You get against certain people -- not to say we shouldn't have thrown out more than we have. It's a work in progress," Gibson said. "There's different things you can do. Mac (Brandon McCarthy) did a good job of holding the ball the other day and (the Phillies' Jimmy) Rollins took off and he stepped off and we got him."
A month into the season, the Diamondbacks are already halfway to the number of stolen bases they allowed in each of the past two seasons (48).
"There's different cadences that you can do," Gibson said. "But we haven't pitched well so consequently more focus goes in other areas. You got to pick your poison. This is uncharacteristic but all the guys are working hard trying to correct that."