They have a good experienced guard in Dennis, and he should be used and play more time.
No question about his capability, he really is a good guard, his team won the FIBA world cup, right? However, even if Dennis is good, he can also be a liability if their opponnents will design a play to attack him since he is a small point guard, so Raptors also need to look at that, I see Dennis as Trae young who is a liability in the defensive end.
Raptors now ranked number 12, so I think every game is important for them to at least qualify for the play-in tournament. However, missing Siakam might be a big problem for them and it started to show their real capability as a team.
Dennis is NOT a liability on defense.
His career defensive rating would give him the top spot of all points guards this season. Sure his DRTG this season it's a bit down because the team also sucks, but he is a very sticky defender. Undersized, yes. But still he is a solid defender and can hold his own on the court.