I think that we're reading this too much with a one-track mind. Perisic brings a lot of strengths and adds some dimensions we've been missing massively on the wings. Overall, I'd say his strengths are:
- Pace and direct running
- Tireless work ethic
- Strength and size too
- Has a good shot on him
His drawback - and it's a clear one - is that he can't cross too well...or at all, depending on how stern your assessment is. This is why a lot of us feel he's not up to scratch as a signing for us. That said, I feel Mourinho is going by the system he wants to play and feels Perisic fits that. He clearly wants a left winger who can cut in and make direct runs or find space inside for someone to find him and of course, be able to score. This would require another key element that we've been linked with for a while now - a LB who can cross and attack well. Add a good LB with a good cross on him and we negate the weakness of Perisic while adding a massive amount to the team overall.
In the current team, our right winger needs to have a good cross, because Valencia - game trier that he is - generally seems to hope that the first defender will deflect it kindly for him, since he can't seem to avoid hitting the first defender every time he crosses. (This of course, is why I feel we also need an upgrade on him at RB despite his performances this season. We can't be CL challengers with Blind being the only FB option we have in the squad who can actually cross the ball.)
All said and done, let's get real. We won't be signing only "headline" players like Griezmann, Bale, James, Ronaldo, Messi etc. We have to be realistic and trust the manager to make the right choices. Bailly was hardly the signing that set the world alight and turned out to be an awesome buy (best defender of the last summer window?). Jose said his list was made months ago and I've learned from experience that when someone as meticulous as him makes a target list, it's generally based on sound logic and reasoning and has a better chance of succeeding than most (though there is of course, always the risk of failure).