Have you considered streaming the matches off of replay files instead of streaming them live (would be like 5-10 minute delay) to cut down on some of the lag and client issues? It seems like most of the issues are caused by network jitter.
Also casters seem to be lost about what to talk about sometimes. I know casters for other games talk about things other than just the game just to keep people entertained. Game topics outside of OWC stuff would tie in nicely (such as opinions on ppv2.0, different mods, "how to get better", etc.). I definitely think there is more they could talk about as far as individual players (perhaps do some research on players and talk to them beforehand?). Also, if you say something about a player in one match, and they play in another match 8 hours later, it never hurts to repeat what you said. Not everyone watches from start to finish. Something just feels extremely lacking and I'm not sure the best way to put it into words so hopefully the above touches on it properly.
TL;DR network problems + casting feels unrefined