For those like you worried about how him playing at Toledo would likely translate to P5 level play, RayJ's closest statistical comparable is Carlik Jones who played at Radford before going to Louisville for a year a few years back. Both players are 6'1"-6'2" 185lb PGs who played 3 years of midmajor ball and had phenomenal junior seasons before going power 5. This is how Carlik Jones' numbers changed and what we could expect from RayJ if he follows a similar track and where he would be predicted to rank in the B10 next season:
Carlik Jones: (Radford (Jr)--->Louisville (Sr), change)
OEff: 1.198-->1.057ppp (-0.141ppp)
eFG%: 53.1-->43.4% (-9.7%)
2pt%: 50.6-->42.2% (-8.4%)
3pt%: 40.4-->32.1% (-8.3%)
AstRate: 36.1-->26.1 (-10.0%)
TORate: 13.5-->12.7 (-0.8%)
STL%: 2.3-->2.2% (-0.1%)
RayJ: (Toledo (Jr)--->Illinois Predicted (Sr), change)
OEff: 1.192-->1.052ppp (-0.140ppp) [52nd in B10]
eFG%: 52.9-->43.2% (-9.7%)
2pt%: 52.3-->43.6% (-8.7%)
3pt%: 36.4-->29.1% (-7.3%)
AstRate: 32.1-->23.2 (-8.9%) [9th in B10]
TORate: 11.5-->10.8 (-0.7%) [14th in B10]
STL%: 2.5-->2.4% (-0.1%) [16th in B10]
So overall, I think some worry about how his offense and shooting might fall off in B10 play is fair based on best historical comparison, but his assist and turnover rates should still translate quite well to B10 play as should his ability to get steals on defense. That said, he would not be expected to be the go to guy on offense for us, so decrease in shooting may not mean as much if he's mainly taking higher than average quality shots due to primarily being a setup man for this team. All in all, should be a very good get for us regardless.