What is frustrating that maybe you didn't understand before is that we're not working together now as it is (in two different cities ... at least a 2hr plane away). For my own saneness, team energy, and for the sake of teamwork, I thought that moving to YC would be a great opportunity for us to actually work in the same room together, and have support all around. I know that if that happens, we will do great things.
btw ... I'm gonna apply anyway. So, you'll hear from me again soon.
I wouldn't describe them as "lame", but they can still be especially risky. They will likely be apt to entertain working on the startup which will be enticing, but you really don't want to get strung along. The sooner you can assess the likelihood they are capable of committing the better.
My guess is that the best tactic in this case is to figure out way to convince them the startup is happening with or without them. Just like investors the best motivator is probably fear of missing out.
It's always a judgement call whether one's cofounders' inability to move is a sign of general lameness, or whether they're so good that they're worth having anyway. But it's that deeper question you need to answer. If your cofounders are lame, you should ditch them regardless; and if they're not, don't worry about YC, because good cofounders are worth more to a startup than we are.