Robertson is 26. The ideal scenario is that he stays fit and in form until at least he's thirty. So four more years. Lewis is 22. In this scenario, he won't hang around for four years as a stand-in, now that he already feels like he's a first team player. So maybe out of a mixture of hope and patience, he'll come here and fight for, say, two seasons before his agent tells him it's time he goes elsewhere to become a first choice LB. That's okay - his sell-on worth ought to get us about twice as much as we paid for him. Now that leaves us with about two more years of Robertson at the peak of his powers. That should be the time when we go for someone about the same age as Lewis now, 22, but with the view to gradually groom him as Robertson's successor. So that player we should really invest in.
Obviously all kinds of things can happen to wreck that sequence of events, but I think the most likely scenario would be to pay low for Lewis, get about two mutually beneficial years out of him, as he gets great coaching and we get a few games, and then sell him on for a big profit and really go for Robertson's most likely replacement.
