It looks like the NBC/Versus plan was simply outbid. Though NBC's piecemeal live coverage couldn't have impressed the All England Club or whoever grants the rights.
Last Monday at one time both NBC and ESPN (on TSN) were both showing the same match (Serena Williams!) with their own commentators. Later in the week NBC's Ted Robinson would say things like "we are now being joined by those in the Central time zone" followed an hour or so later by "we are now leaving coverage in the Eastern time zone but will be joined by those in the Pacific". I'm guessing some Americans had to switch to ESPN (maybe ESPN3 online) to get the full coverage of a match they started to watch. Obviously NBC didn't want certain programmes in their day time line-up to be pre-empted for Wimbledon thus the confusing back and forth. Judging by the responses at the NY Times tennis blog most fans are happy to see the back of NBC.