Time for a change in Arizona?

Pinto on the amazing fading Diamondbacks:

    The Arizona Diamondbacks are in one of the worst team slumps I can remember. Felipe Lopez, a most unlikely hero, is hitting like an MVP but the rest of the regulars are not producing. Three players with at least 20 at bats are hitting below the Mendoza line. Three are posting OBAs below .300. The slugging percentage column shows values of .130, .231, .233 and .300.
    Conor Jackson, Chris Snyder, Chad Tracy, Mark Reynolds and Chris Young were all good minor league players who have plenty of major league experience. We should be seeing these player improve instead of regress. Stephen Drew is not young. This is his age 26 season, where he should be at his best. The only one I give any excuse based on age and experience is Upton.

    This is a team that should be gelling into a group of above average players. At what point do we start blaming Bob Melvin and his coaching staff for not developing this talent? The biggest mark against the DBacks right now is Carlos Quentin who went from good to bad under Melvin, then blossomed under Ozzie Guillen. Maybe it's time to get a mean, nasty demanding manager pushing these hitters to play up to their potential.

I'm not going to suggest that the Diamondbacks might not benefit from a new manager. I will point out, though:
1. It seems to have been the front office that gave up on Quentin, which became obvious the moment Eric Byrnes got his big contract extension (which as you might recall, didn't make much sense at the time).

2. One year ago, the Diamondbacks got off to a fantastic start -- 20-8 at the end of April -- mostly because their young players (as I recall) were putting up fantastic numbers. Do 12 games this April tell us more about Bob Melvin's impact than 28 games last April?

In the absence of easily identifiable mistakes -- say, the sort that Trey Hillman makes every few days -- I'm going to give Melvin the benefit of the doubt for now, and assume that the front office will be ready to make a move if it seems that Melvin has lost the clubhouse.