Would a young player (under 20 as an example) who has ability and significant potential realise that potential sooner if they play 5 or 6 games for Wasps in the premiership, or by playing ~20 games in the championship?
Let's use Umaga as an example. We currently have WlR in the squad.
I think everyone would choose WlR when we're up against Exeter and Saracens - if nothing else, it would be unfair on Jacob to through him in against those teams when the rest of the team is likely to struggle as well.
We then have the other teams around us battling for Top4/6. If WlR is available, how many of you feel that our chances of winning are improved by putting Willie on the bench and starting Umaga against Gloucester, Quins, Sale, Tigers, Bath?
Maybe he starts on the bench and gets 20 minutes in a couple of those games.
We then have fixtures against the teams at the bottom (I don't want to call them weak teams, because they've beaten us already in some cases), Bristol, Warriors, Newcastle.
Let's say we start Umaga in those games home and away and all goes ok.
That's 6 starts and maybe a couple of bench appearances, whereas he's likely to get 20+ starts in the Championship.
If he's enjoying it at Carnegie, then it probably helps him realise his potential by playing more often and experiencing a wider variety of opposition.
For the same reason, the loan spell in NZ was also hopefully a great experience to help him become the player that we all hope he will be.