Makes sense really. I rate Willis very highly but in terms of who's going to bring more impact from the bench then it's undoubtedly Earl. I think Willis is definitely one of those players where he either starts or he isn't involved at all.
There are many things you can want from a bench player - and most of them will depend on other factors, like who's starting, who is elsewhere on the bench, and to a degree, who the opponent is.
The single most important aspect of the bench is to cover in case of injury - so versatility is good, though that need can be reduced depending on who else is where.
Next probably comes "impact" but that comes in many different forms. Pace is useful, but so is power - especially if you bench player means that your prime bosher can expend all their energy in the first half, softening up the opposition. Turn-overs are also a form of impact, more likely to be successful against a tired team.
There's also a place for a cool, calm head - a player-coach; who can provide "impact" by getting his team back on the right side of the ref, and not giving away a penalty every 5 minutes, or making it less likely to double up on offences.
And finally, there are some games, when the most important factor for selecting a bench is to build for the future - to introduce an inexperienced international in a kinder way - setting them up to succeed; or to try out new combinations in a low-pressure test match environment.
For me, this entire Autumn window has "building for the future" as the single most important aspect. Against Italy, the bench won't be the difference between a TBP or not. It may just be the difference between a big score and a huge score - but not to the point where I feel we need to worry about it - especially in a 6N that's more for the history books than any current value.
Then we have 4 meaningless fixtures against Georgia, and a trio of 6N sides we'll be playing properly in a couple of months time.
