Anecdotal evidence: For about ten seasons, my Portland staff's top two starters had GB/FB ratings of 29 and 93.
During that time, the 29 guy had a Groundball ratio of .9:1. The 93 guy, 2:1.
The 29 guy gave up about 300 HRs, the 93 guy about 200.
But in every other way, the 29 guy put up consistently better stats all the way around. Similar control, but the 29 guy had superior vsR and great pitch ratings.