What I want to see more of is how he deals with crosses, especially given his height – that element could determine whether he will become a top goalkeeper or not.
Absolutely. I don't care how good the rest of his game is if he comes into the PL and suddenly finds himself under real pressure. Crosses are a real weakness for us at the moment and we need a keeper with Ming's shot-stopping ability plus the aggression and confidence to come and win crosses and totally dominate his box. Including stomping on the balls of any of our defenders that pfaff around. I really think that he is too short regardless of how agile and good a shot stopper he is.
Look at the list below, only Casillas and Valdes come close to that. No coincidence then that they can survive and thrive in La Liga, which generally has less physically aggressive players.
5'11" just seems too short for a top keeper :
Lloris : 1.88 m (6 ft 2 in)
Neuer : 1.93 m (6 ft 4 in)
Casillas : 5' 11"
Courtois : 1.99 m (6 ft 6 1⁄2 in)
De Gea : 1.92 m (6 ft 4 in)
Cech : 1.96 m (6 ft 5 in)
Stekelenburg : 6' 5"
Sirigu : 1.92 m (6 ft 4 in)
Buffon : 1.91 m (6 ft 3 in)
ter Stegen : 1.89 m (6 ft 2 1⁄2 in)
Hart : 6 ft 5 in (1.96 m)
Valdes : 1.83 m (6 ft 0 in)
Weidenfeller : 1.90 m (6 ft 3 in)
Butland : 6 ft 4 in (1.92 m)
v.d. Saar : 6 ft 5.5 in (1.97 m)
Reina : 1.88 m (6 ft 2 in)
Schmeichal (original) : 1.91 m (6 ft 3 in)
Gordon Banks : 6 ft 1 in (1.85 m)
The Premier League in England consists of 20 clubs. The average height of the 20 first-string (or first-choice) goalkeepers is 1.92m (6 feet, 3 inches).