At the beginning of their career I used to absolutely hate the Nevilles player wise. Their positioning was iffy, their tackling was rash and they weren't really physically imposing. I felt guilty about it because they were fantastic kids. However their mistakes costed us. For example we were at an inch away from losing the treble because of Philip Neville's tackle against Arsenal in the FA semi final cup. If Irwin was a ferrari, the Nevilles were a skoda.
Sir Alex would not listen to any criticism about that. Week after Week he would play Gary Neville irrespective of any mistakes he might do. There was a time when he even tried to play him as CB which proven to be a disaster. Yet the man didn't lose his cool, he stuck to the guy and he turned out to become a fantastic servant to the club. Sure Gaz never reached Irwin's heights. However his positioning improved, his tackling became less rash, he became a leader and years training with Beckham made him quite decent going forward as well. At one time he became the best RB in the nation.
Years later the strategy seemed to have changed. We secured Jones and Smalling early so they can be brought in the first team slowly. Sir Alex gave them as many games as possibly usually as RB or as DM. Unfortunately the experiment ended up failing big time. Smalling might have trained with Vidic but he was nowhere near as good to Nemanja. Same with Jones who is as close to Rio in terms of talent as a Christmas pudding is to Lionel Messi.
I am not a big fan of AWB. I think his game is somehow limited and he's nowhere near in terms of talent to the 50m fee we paid for him. However if we believe in him then we should play him week in week out. That's how players improve. Adding Trippier will only strip AWB of his confidence and that precious game time need to polish any potential rough diamond.