Ches is very very good. The Lawi Lalang transitive property hypothesis is also sound. He is not far from the elite level. He could give Rupp some trouble in a non-peaked casual performance. However, even though he can close NCAA outdoor 10k super fast, he won't be able to have a fast kick in a faster race where Rupp can still maintain a fast kick. Ches is absolutely nowhere near the level of the silver Olympic medallist who two years + straight has showed sub ~26:45 fitness. There is no American in history who has been near that level. If Solinsky hadn't gotten injured (which is a huge bogus hypothetical, as the same training that got him to great heights probably took him down), maybe. There is no discussion at 10k. Maybe if Ches goes sub 27 sometime in the next 10 years. It's not a walk in the park to do, even for a talented Kenyan.
3k/5k is another similar story. Rupp is our top distance athlete. He's been competing for the upper echelons for a number of years now. 3k/5k, in championship and diamond league races, he's put himself there. Contrary to what most haters say, it is very competitive around 5k and the top studs often trade positions. Some show up one day, some don't. It's a game of statistics. Ches right now could not hang with the tactics of the top Ethiopians and Kenyans. They close those 3k/5k races viciously. E.g. if my memory serves me right, the olympic 5k was closed in 2:35, then 2:25. Even in races when it looks like it came down to a kick at the end, it is usually more prolonged and subtle than that. A kick in the NCAA is not the same as what unfolds on the Diamond League/World Championship level. Ches is not sub 12:55, Ches is not sub 7:30. End of story.
If the race is unevenly paced and Rupp is not on his game, fitness or motivation, than Ches can challenge over the mile. That's it.