He wasn't that great. He is notorious in the big five-sided building for taking existing concepts, changing one element, and renaming them to make himself look like a genius. He begrudgingly took the Deputy job assuming he would get the pilot seat eventually, and when it didn't happen he made everyone under him miserable for months, myself included. He may have been able to pull off some astounding back door acquisitions while he was the AT&L Director, but he added no value as the DSD.
The Department would do well to have someone like Frank Kendall or Bob Hale in that slot. Both understand well what warfighters actually need, and both are fiscally-minded. Neither are social climbers or power hungry ass hats.