Except, its NOT designers who are to blame for bugs, but developers.
Not the guys coming up with ideas and balance, but the ones who code.
The majority of the changes in these patches are just tweaking scripts and unit variables. This is something a balance designer would normally do, not a programmer.
If you remember, they said the delay to the original vet-fix was they needed programmers to do some fixing (meaning it was outside of their abilities).
The majority of bugs and issues with the game was down to the poor QA and shitty work done by Brad tweaking the games high level scripts and unit variables. I honestly believe he was let go due to the embarrassment of the patches.
Every game company has tracking and statistics involved with every patch launch and the leads probably noticed the amount of patches and hotfixes for the patches and hotfix for the patches patch that kept happening.