We've also got to remember why Earl's being considered there - it's because he brings an exceptional combination of power and pace and could possibly regularly get us going forward. To get the shirt, all the other names being bandied about also need to provide some really exceptional attributes - which might be similar to Earl or completely different but they need to bring a USP. And show it over an extended period of time.
We talk about 'glue' players but the best 2 examples I can think of who got that epithet are Richard Hill and Kruis - neither of whom did the glamorous stuff but both of whom made players around them look better. But they weren't average or sort of OK, as I'd say Dingwall is, both were good enough to be World XV players. Might be being unfair on Dingwall there, but let's see if he gets the chance to prove himself against proper opposition.