They are playing Raman upfront. Not for the first time this season either. Burgstaller is painfully mediocre, so it's not odd for him to sit on the bench. I guess Wagner hoped for Raman's pace and trickery (relative to the rest of the squad) to have an impact on counter attacks.
Schalke's keepers are a quite the story this season. They had an option to extend with Nübel but forgot to exercise it in time, then when they made a normal offer for an extension his agent said "first you didn't want to, now it's too late", so went into the season with his contract expiring, apparently turning down a couple of decent offers (€10+m) and hoping to convince him to stay after all by making him their captain. They also signed another promising GK talent in Schubert from 2nd divion's Dresden. Long story short: Nübel made some errors, got send off and suspended accordingly for four matches around the turn of the year, right when he announced his move to Bayern. Schubert then enters the goal, there's a lot of talk about him displacing Nübel for the rest of the season, but then he blunders horribly too, so Nübel returns into the starting XI after his red card suspension, but then he keeps blundering again, so they switch back to Schubert, who too, can't keep from blundering.