Its not just goals. Tello is insanely fast, tricky, an adept dribbler, and has a great shot. He is somewhat one dimensional and not creative but it's not like his playing style requires him to be. All Alexis has is a good workrate and stamina but nothing else. Tello provides something different to the squad. He gives a different style of play when the rest of our offense is lacking and unmotivated. Alexis doesn't really provide anything special or new and isn't great coming off the bench or as a starter.
"insanely fast, tricky, an adept dribbler, and has a great shot" all fall under the heading of 'Goals', Am i right, What you want add is, Off the ball movements, Creating spaces and tracking back, Which are all near zero for tello, And all of these are a 'Must' present qualities in our wingers, These aren't optional luxurious bonuses, That's just how our system works.
The only reason why we aren't seeing the negative outcomes of these shortcomings of tello is because tito doesn't let him play much, And thank god for that.
Alexis simply because we need the defensive cover with Alves constantly bombing forward and Bayern and Juventus both being an extremely dangerous offensive threat. However, when Montoya matures (who seems to be much more defensive) I would pick Tello in a heartbeat.
You can apply this to any team , Nothing particular about these two.
But now that we're at it, Tello...dangerous offensive team, mmmm that does seem to ring a bell, oh yeah it's one with real madrid, Well that worked out splendidly, And as i remember his defensive shortcomings weren't standing out actually, Because he was horrendous in pretty much everything else, In his defense, He did seem to bore arbeloa to the death with the same trick, I'll give him that.