He has tended to have a player that can offer the most cover in the 23 shirt. It's not always a back 3 player. With Farrell in the 22 shirt, able to cover 12, we arguably need someone who can cover 13 and fullback, seeing as Joseph can cover the wing, and neither Farrell nor Ford cover fullback (like Cips).
I really cannot agree with this in the slightest and wonder if we're using entirely different definitions.
We've just gone through a window with Twelvetrees in the 23 shirt covering 12, just 12, and necessitating a shuffle if there was ever an injury anywhere but 12.
Prior to that we had Yarde on the bench, just covering wing, with Watson on the bench for one game.
Out in NZ it was Ashton once, Burrell once, Pennell once. By my count, that's a solitary two in twelve games where the guy in the 23 shirt is genuine international class in two or more positions, which is being slightly generous to Watson at full-back and Burrell at international rugby.
Going further back, you have that interminably long period with Alex Goode at 15, with all the attending disasters of Mike Brown on the wing it occasionally brought... Manu's been on the bench a couple of times, and he's sorta versatile, but he's only on the bench to regain fitness, Foden at 23 once, he did ok at wing I guess, Strettle once...
In short, going back to 2013, Lancaster has shown absolutely zero qualms about sticking in a guy that covers one position and one position only in the 23 shirt. If you call that offering the most cover, we are using entirely different definitions. To me, it says very clearly that Lancaster is in fact doing the opposite of what you say, does not care at all how many positions number 23 covers, and that being able to cover multiple positions (in theory at least) gets you nowhere with him. Elliot Daly is quite clearly not Lancaster's dream of a 23.
Oh, and Watson will probably be covering 15 from the wing, and Nowell's claim to covering 13 is as good as Daly's to covering wing. And full-back too. So, it's a fairly flimsy argument that we'll need someone who cover 13 and 15 from the bench - unless you want someone who come straight onto the pitch from the bench in any position without any reshuffle, which is a decent idea, but not one Lancaster has shown the slightest interest in.