The Arizona Diamondbacks are not getting the type of production out of their top stars they've been used to in their recent stretch of play. Ketel Marte and Corbin Carroll — both touted as two of the more dangerous, electric hitters in baseball — have been on a bit of a skid at the plate. Carroll has gone 1-for-his-last-14, while Marte snapped an 0-for-13 stretch in the D-backs' 9-0 win over the Pirates on Tuesday night. It's worth noting that Marte did hit a triple and a single, and reached 600 career RBI during that game. But his season numbers are still ugly, with a .221/.277/.374 slash and .645 OPS on the season. Carroll's season numbers are prettier, but have sunk to a significant degree. Hitting .312/.413/.610 on April 22, the outfielder is down to .268/.371/.509 — still productive, but less so. So what's been going on with the two stars? Manager Torey Lovullo broke down the situation in Tuesday's pre-game availability.…