Ahead of Luamanu at No 8 are a current international captain, an England international (albeit one who seems to be permanently crocked) and a former JRWC captain (who you would hope would get a crack at the senior squad if he stays fit, in 2020 if not before). It’s not surprising that we don’t see him much in the first team.
I’d like to see if Gustard and Quins can do for Mat what Sarries have done for Will Skelton. Skelton was an overweight lump last season but has lost about half a ton over the summer and looks far better for it. I think Luamanu could be far more effective at both lock and No 8 if he could lose some of the bulk.