We know that Monte wants to build around Fox and Sabonis. We also know that he'll take whoever he thinks is the best player available even if it's another guard since he's done that the last 2 years.
Ivey can play on or off the ball and he is big enough to play SG full-time. He didn't get officially measured at the combine but if he's got a 6'9 wingspan as reported, that's average length for a SG.
@funkykingston and a few others have argued that putting Ivey at the off-guard position limits his star potential which is probably true but I don't know if that's a big enough reason not to take him. And it may actually be a good thing for his development if he isn't asked to be the lead ball handler on a last place team as soon as he gets to the league. He also name-checked Davion Mitchell in his film session with Mike Schmitz as the guy he most wants to model himself on defensively so getting to go against him in practice every day is at least one reason why he shouldn't be upset if he gets drafted by the Kings.
Murray is in most people's top 5 at this point so taking him at 4 isn't really a reach unless you think Ivey is levels of magnitude better. I like Ivey but I don't think he's a guy you need to take no matter what and I think Murray is at least equal to him as a prospect when you factor in his defense and production in college. He's a guy who easily slots in to our lineup and I think based on his interviews he already has the maturity to handle a starting role on a team with playoff aspirations. That means digesting the film sessions before and after every game and being able to make the needed match-up adjustments.
I haven't seen any reports connecting Mathurin to the Kings but if Monte thinks Ivey, Murray, and Mathurin are comparable as talents and as fits then it would make sense to trade down either to 5 or 6 and know that we'll be able to get one of them. Since Mathurin can play the 2 or the 3 and is already an elite catch and shoot player I think he's an even better fit for us than Keegan Murray but most of the draft evaluators seem to see him as a clear level of talent lower.
The real mystery to me is what happens if the top 3 don't go as projected -- if Ivey or even Murray go higher than expected and we have one of Holmgren, Smith, or Banchero available to us, does Monte take them? Holmgren could slide if his team continues withholding medical info and then we're facing down the ghosts of every other top 5 drafted big man with medical red flags who had truncated NBA careers. Banchero could slide if OKC falls in love with Ivey and Orlando takes Holmgren. Does Monte take Banchero knowing that he doesn't project as an elite shooter or an above-average defender? I would expect Smith is an easy pick to make if he's available but I'm also in the minority here as I would be disappointed if we end up with Smith instead of Ivey, Murray, or Mathurin.