On Soccerway I note PSV only listed a 7 man bench for this Europa League clash.
But for Eredivisie games they typically list 11 on the pine.
Maybe the 2 comps have different rules re replacements.
Ain't going to be easy for Thomas at all, to get playing time. PSV unbeaten after 8 games in Eredivisie, and again look to be in a head to head battle with Ajax for the title (also unbeaten).
He may ironically need some injuries to occur, to get a look in.
PSV are top of their Europa League group, with 2 wins from 2, show there maybe some dead ties in that comp coming up.