Augsburg fans (and journalists) have been pretty adamant that Schlotterbeck does make quite a few mistakes and apparently had a bit of a stinking pre-season... so it probably wasn't a one-off at Birmingham. They just appreciated his commitment and aggression and felt that over the longer run it made enough amends for the mistakes
Yes he is better on the ball, but he tried to be too clever against Watford in an attempt to retain possession and paid the price for it. Wood just gets rid of it more often, which does alleviate pressure but just coughs up the ball to the other team higher up the pitch, which is probably something that coaches don't necessarily appreciate either