I think it's safe to say the chances of Harper being a wildcard in the squad any time soon are quite low.
Malaga signed 4/5 players in January and they all seem to be getting game time. The signed another big lump of a striker, so Harper is basically 3rd choice there (in a team that's starting to play 1 up front more often). They've also signed a young guy on loan from Getafe, gave him the No.10 kit and he's starting in Harper's usual positions a lot of the time.
Harper's averaging 20 mins as a sub over the last three games and could be stuck in a rotation for a wide place in midfield.
From watching 5 or 6 of his games this year, I'd say he's a decent player but doesn't have much of a spark. He doesn't run at defenders much, he's not a great goalscorer. He's just kind of there. Making the odd good touch or turn, and constantly pressing the opposition (which he gives away a ridiculous amount of fouls for). Maybe the muscle injury from a few months ago has affected him a little.
I'd still like to see him get a chance at some point. San Marino would have been a good chance for him to come on as a 2nd half sub but it's probably came too soon.