Why is He Here?

Mitch Walding was summoned from AAA to take the roster spot of injured infielder JP Crawford.  This is Walding’s second time up this season, and he’s hitless in 7 at-bats with 7 strikeouts.  

Walding had OK numbers in the minors, but he seems either overmatched or extremely nervous.  But when he came on to pinch hit in the 8th inning today, all the Cardinals infielders shifted to positions between first and second base.  The whole left side of the infield was empty. The situation screamed for a bunt attempt. Walding didn’t bunt. He struck out for the 7th straight time. 

Why didn’t he get the signal to bunt? Why didn’t he do it on his own? Is this the best guy the Phils have in the minors to fill an infield hole?