Mastro is my adoptee so I'm obligated to second this. Still, I'm not sure his skill set matches what the Twins need, and I think that's why Clete has gotten chance after chance. Clete has most of what Mastro has, speed and defense, to a lower degree, and brings a moderate level of power based on his minor league production that Darin just doesn't have; they both show about .750 OPS in their time at AAA, but Clete's was achieved differently. In yesterday's no-hit game's lineup, three of the hitters (Span, Casilla, Carroll) are clearly table-setter types, Willingham has demonstrated RBI ability, and we can debate the spot on this spectrum for the other 5, all of whom have potential to do more than set the table but currently aren't doing much else (in some cases like Plouffe they aren't doing anything at all). Replacing Clete with Mastro in that lineup gives you four table setters. Moreover, Mastro's best role is as a leadoff hitter, and Span's not moving out the way for him; batting him #2 would likely waste his strengths, and batting him 9th seems weak to me. Particularly until Morneau shows he's ready again, t's just not a fit right now. Now that I think about it, I wonder if Mastro was signed specifically as Span insurance in case the concussion symptoms recurred. If so, we kind of have to hope he remains buried at AAA. Sorry to have to say that about my adopted "son".