Yamcha is weaker than Krillin. He was never stronger than Krillin. But even though he is weaker, I think 23rd WMAT Yamcha could beat 23rd WMAT Krillin, but that is since Krillin was weaker than Kami. It's all a matter of technicality, though. The answer is that Yamcha is for sure not near as strong as Krillin and will never be. Of course, it's a matter of opinion, but that's my opinion, and, according to the information given, that's just the hard, cold facts. Some don't think that Yamchs is weaker, but if you put them up, side by side, or consider any of the battles they have fought in the past, you will see that what I say is right on.
There is always the possibility that he will gain new power, and therefore, the entire scenario would take a big turn about. It would, of course, depend upon what that new power was if it was enough to make him that much stronger or not. That's what keeps you glued to the edge of your seat with this series. Nothing is certain in this series, which is precisely what I love.