The gaps we leave on the pitch between full backs and midfield are horrendous. You're right, it's meant he's had to cover far more ground when the opposition are counter attacking which basically makes him, and others look like they're miles behind play. Hunting in numbers close together over those 10 yards will work so much better.Silva etc might actually be able to do some of the stuff Pep requires if they are playing in a balanced team, & getting plenty of rest inbetween.
Being asked to track back 60 yards after 20 year old wingers with Kolarov & Yaya Toure as the nearest help, is unlikely to be a situation Silva will ever face again.
He may have to do lots of small 10 yard covering runs instead, as one of a large group, all doing the same, & which he may actually have no problem whatsoever doing.