Test for Underpitched Oktoberfest (WLP925)?

[HiFives]

The grain bills were quite different... both were single infusion mashes at 152F. We had some temperature control/consistency issues with the infusion, and a large percentage of our malt was quite old.

Was this attenuation difference between two exactly identical grists using two identical mash regimens or between different recipes, etc.?

[brewmaster 2011]

How old was the malt and was it premilled?