If JDS's jujitsu was better than Mir's (as his trainer said), then he certainly could've offered more resistance on the ground. I, and imo others, may have overrated JDS's jujitsu.
Nothing against talking good about your student, but it shouldn't sound that ridiculous. Dos Santos never has really shown any BJJ worth talking about. As I've said here
two weeks ago, recent footage of him rolling with Machida didn't show much ground fluidity. While Mir, almost TKOed and with one foot in lala-land, submitted Nogueira of all people on auto-pilot.
Dos Santos might "know" consciously all the techniques, but it's probably not "natural" to him yet. It takes years. It's like when learning a new language. You may now the grammar rules and have a big vocabulary after 3-4 years, but it takes more until you can use the language without thinking in stress situations.