I don't think I can add anything more to this thread. Edward's post is sufficient to me but I'll add my 2 cents given the low posting traffic around here
My general mantra in these kind've spots is: Never call marginal when you have all suits blocked. The theoretical cost of a euchre is at its highest point when you have a strong defensive holding that blocks all loners. In these situations one needs to tighten up their calling frequency. Conversely, the theoretical cost of a euchre is close to it's lowest point when you block no suits and thusly in those situations one should feel impelled to call very loosely.
So let's look at Richard's holding in the 1 seat after the KC has been turned down:
If Richard had to call here he should call Next. IME calling Next with Left + 1 and an off ace + no voids is a marginal holding. One should expect their euchre frequency to go up significantly when they make this type of call. Is the risk worth it? I would answer with an emphatic no! Look back at Richard's hand. Not only does he have all suits blocked, he even has a euchre hand--albeit a weak euchre hand--with approx 2 tricks in every suit. Again, I pose the question: why call marginal when you have such a strong holding if you pass? One should save their marginal calls for hands that block nothing or don't have reverse next fully blocked. That's what marginal S1-R2 calls are for.
What actually happened in the hand is kind of a bad beat. Seat 2 has a hand that is very close to the top of his range in this spot and subsequently his teams gets a relatively stress free point. But focusing on the results is missing the bigger picture. Think about how wide S2's calling range will be in that spot, and then think about how S1's team will do against that wide range given S1's strong holding.
Ok now let's look at Edward's S2 holding after the dealer turned down the KC:
Here Edward has a very strong euchre hand. Not only does he have all suits blocked, but he has approx 3 tricks in a heart call and a Next call. Edward has approx 2 tricks in a diamond call. Yeah Edward could call hearts here--a solid call certainly--but it's still no world beater. Ed still only has 2 trump and no voids and only 1 off ace. It's a good hand but not a great hand. With such a strong euchre hand I'd much rather pass. And by passing in this spot Ed gains in 3 different ways:
1) He can trap S3--a very agressive player--into a euchre.
2) Those times S3 passes, the dealer will call a hand that is more likely to line up with Edward's holding than had Edward called himself. No matter what the dealer calls he can't miss lining up with Edwards hand, but if Edward calls he can easily "guess" wrong.
3) Another small but underrated benefit to passing this holding is the fact that once Edward passes there is only 1 team that can get a 4 point sweep. His team. There's value in that and that value goes up with teams that know how to read hands well.
Here's an example of good hand reading.
Score is 0-0. The dealer passes the upcard

, my clone in S1 then passes, and S2 also passes and I'm in S3 with:
or I have:
What should I do?????
In both cases I should go alone in Clubs!!! Why becuz when my clone passes in S1 he will always have reverse Next blocked thus taking key cards out of the equation that turn my marginal loners into power houses (S1 is not guaranteed to have Next blocked as that is not his job defensively speaking so that's why S3 should not go alone in Next in the 2nd hand).
Now back to Edward's hand: when Edward passes in the 2 seat in that spot there's a very good chance he has all suits blocked and the dealer can astutely use that information to his and his team's advantage by going alone a little weaker than normal. Think L+1+2 off ace type holdings, etc.
Now in the actual hand S3 makes a thin but good diamond call--the suit Edward was the weakest in--and ekes a point through. Another bad beat as far as I'm concerned. One should not let the results of the hand cloud their judgement. Sh** happens sometimes, but Edward made a good strong pass for the right reasons.