Well taking the Under21s and winning the Euro Championships is quite an achievement, yes his league record early doesnt hold up to as much success as his England coaching/management but he has served his time at many clubs from Coventry, Sheffield Utd, Birmingham, Manchester City academy and Brentford and was well thought of, if not succesful all through that period, he has obviously some attributes that are well thought of to be given a chance with the Full England squad. It may not tick all the boxes, but it certainly ticks a few, young, progressive, great network around him, works with top players at England level and has got them playing well, So far.
It would be a punt, but so will anyone who comes in!