He's also well ahead of the pack on the Prem's EA Sports Player Performance Index. He averages 16 (points?) per game compared to Cech on 14 and Lindegaard, Lloris and Hart on 13. No idea what's being measured, but when two completely different ranking systems agree to that extent it's got to mean something.
whoscored.com covers the 5 major European leagues. Overall De Gea is ranked 6th, although only one keeper, Iraizoz of Bilbao, is more than 0.02 ranking points ahead of him. (To all intents and purposes he's in a 5 way tie for second.)
Hmm... On the WhoScored.com ratings: they're very interesting, but have to be seen in the right context of course. Goalkeeper is probably hard to define in terms of statistical weighting, IMO there's a huge "bias" towards shot-stopping. Watching their performances is a more important indicator *duh*. Let's see.
#1 Gorka Iraizoz (Athletic), 7.09 (from 24 league apps)
#2 Toño (Granada), 7.02 (from 21 league apps)
#3 Dani Hernández (Valladolid), 7.01 (from 20 league apps)
#4 René Adler (Bayer Leverkusen), 7.01 (from 24 league apps)
#5 Ron-Robert Zieler (Hannover), 7.00 (from 25 league apps)
#6 David De Gea (Man Utd), 6.99 (from 20 league apps)
#7 Marc-André ter Stegen (Mönchengladbach), 6.99 (from 25 league apps)
#8 Fabian Giefer (Fortuna Düsseldorf), 6.98 (from 25 league apps)
#9 Mariano Andújar (Catania), 6.98 (from 28 league apps)
#10 Willy Caballero (Málaga), 6.97 (from 27 league apps)
Iraizoz at #1 is bizarre by all counts; not only have Athletic been having a horrible season (conceding 50+ league goals already), he's been guilty of making mistakes to such an extent that 18-year old Raúl Fernández has been preferred in the past few weeks. I imagine it's because he faces so many shots per game, that it actually has the effect of boosting his WhoScored rating.
Toño is an excellent shot-stopper and having a good season (personal opinion though), Adler, Zieler and ter Stegen are rated highly in the Kicker ratings I believe (although they have a very big bias towards keepers). One notable name that's missing for me is Thibaut Courtois, who recently broke Abel Resino's club record of minutes without conceding. Willy of Málaga has been the stand-out performer for me though, looking good to win the Zamora (Courtois is also in contention) and been spectacular domestically and in Europe.
My personal ranking of keepers this season;
#1 Caballero
#2 De Gea
#3 Buffon
#4 Courtois
#5 Lloris
Buffon and Lloris not mentioned before, but both impressive every time I've seen them; assured, composed, comfortable keeping for the most part, interspersed with magnificent saves and accurate decision-making. Usual suspects like Casillas and Valdés having very mediocre (not poor per se) seasons; Neuer unimpressive, Hart great in flashes, sloppy rest of the time; Diego López (Real Madrid) has been decent but too early to tell. Abbiati has been incredible most of the time I've seen him so would probably have him at #6 (mostly based on CL games though). Mignolet (Sunderland) has been brilliant at times, perhaps deserves a spot in a seasonal top 10? Am least knowledgeable about Ligue 1, but L'Équipe have rated Rémy Vercoutre (Lyon) as the best keeper, based on their match ratings, but he's been appaling in the Europa League, making so many mistakes in every game I've seen.
Well, that escalated quickly.