I have a buddy with 6 maintenance crews. He had a pretty good way of checking on their productivity. He had all of the crews keep track of their times. They wrote the time the got to the site, and the time they left the site. After a few weeks of doing this, he started to randomly go out with a different crew for a day or a portion of the day to observe them working. What he found was that when he was with a crew, they were about 20% faster on property. He only observed them, he didn't help them at all. What it did was show him that all of the guys were slacking when he wasn't there.
Like spazfam said above, changing the crews around could help. You might find a combination that just naturally works better together.
Why do people not respect us as they do other tradesmen? Because every Tom, Dick, and Harry doesn't think he can be a plumber or electrician!