First off, it's obvious why the show drew a bad rating. It wasn't a good show, and there was plenty of other quality stuff to watch that night. That yields a 2.7, plain and simple. Moving forward, the show will most likely be better with probably less quality competition from other channels, and will get back to the 3's.
That being said, I don't see how anyone can say the WWE overreacts when Raw draws a bad rating. Raw is the flagship show of the WWE, a huge, publicly-traded, global company. One bad-rating show might not mean much, but if all of a sudden there were a few in a row, heads would most likely roll and revenue could potentially be lost. There's a necessary reaction ("overreaction", as some people are calling it) to return to top-form quickly so the aforementioned slump doesn't occur, as people's jobs are at stake, as is the fiscal success of the company. Another factor is that if wrestling were very hot right now and if WWE had 0 competition, then they may not care as much about this either. But in reality, it's not a perfect world for WWE right now, as the popularity of wrestling is down huge right now and TNA is still around.
Business-wise, the WWE is already unhappy and unsatisified with its low 3 ratings, so when they occassionally dip down below that mark, it sparks an understandable concern that forces them to do everything in their power to get back up to the 3-mark. (If you get a bad grade on a test, aren't you sure to study harder for the next one in order to get back on track?) Each sub-rated 3 show may not seem like a big deal to us, but it's the WWE's responsibility to get back to top-form, produce a better show the following week, and pull their ratings up, for the sake of their business. Don't forget, it's still a business, and when a business flounders (even for a temporary period, such as a week), the businessmen that run it are sure to react and do something about it.
Even though the WWE pulls 3's most weeks (and has done WAY better in the past), right now it's an obvious struggle for them to pull those numbers, because each year their ratings have continued to decline. For a company that's looking slightly worse year-by-year in the TV ratings department, I don't think you can really appropriately use the term "overreaction" when describing how they handle their worst rating of the year.