Come on man, use your context clues. Here's a hint: I thought his contract ended in 2016.
Even Pedro now is rotting on the bench behind our usual trio to the point that he's reportedly going to look for a move this summer, and in the public eye he's a much better player than Tello. Bringing Tello back now would actually have him in less favorable conditions than when he was benched before, because at least in 2013/14 one could reason that Messi and Neymar were the only irreplaceable forwards, and in 2012/13 the only one was Messi.
Unless you think Lucho, who won't give Deulofeu even a single game as a first team player because he's a winger who likes to dribble and lacks solid decision making, would for some reason give Tello a chance despite basically fitting the exact same profile.
Well, if Lucho is unfortunately still coach by next season, anyways.