Isn't that just basically a 4-3-3? His formations for Chile were like the too, they were great to watch in the last World Cup. Can imagine the massive headfuck he'd cause for all the thick pundits if he was managing in the premier league. Last season they acted like they'd never seen three at the back before so god knows what he'd do to them.
most teams have various actual formations, depending on the phase of play (e.g. 441 when defending/424 when attacking) but what the manager sets up, and the heatmaps are what tell the 'true' story.
Think it's hard to judge a keeper who makes lots of saves for a team fighting relegation - people don't tend to dwell on any mistakes they make as much as when it's a keeper that hasn't had much to do.
He's great. He's a leader and a character, an ace shot stopper and has great distribution. Look for his long ball assist for England u21's on YouTube for an example.
Obviously it's hard to value players in this market but his best years are definitely ahead of him, so it could be a decent investment for the fee.
Goalkeeper is the one position we've generally been pretty well stocked in over the last decade or so and in a short time playing for us he's managed to really stand out.