I don't think there's any scenario where Kelvin wouldn't push from the front, because otherwise he has zero chance if Jakob is in control of the race. It would all come down to who's in control; if Kelvin for whatever reason let Jakob take the pace it's over for him. But if he's pushing from the front he'd have to have dropped Jakob by like 4 or 5 miles in. I just don't think that would happen.
They both can probably run like 26:20 or so but I feel like in any scenario the distance is short enough that Jakob could probably adjust to it better than Kelvin would - 10k is a massive drop from the marathon, not nearly as much moving up from 5k. In addition, Jakob obviously have tons of cross country experience and has run a 10k on the roads before (which was a comfortable win for him in like 27:54 I think).
They'd both have to adjust to the distance but I think Jakob would have an easier adjustment, since it's so much closer to his wheel house than Kelvin's. Either way this needs to happen! I'd love to be proved wrong haha.