Van Garderen and teammate Mathias Frank held on to their 1-2 on the general classification, with Garmin Sharp's Tom Danielson 12 seconds back on the Swiss rider, but BMC needed to be on their guard throughout the 185.4km sixth stage.
"The attacks were just going non-stop," van Garderen said. "For a lot of teams, this was kind of their last chance to try something. That made for a hard, fast race."
The team also lost the services of Stephen Cummings who was forced out of the race mid-stage, just a day after narrowly missing out on the podium for the individual time trial. The attacks which punctuated the stage, eventually won by Peter Sagan (Cannondale) proved too much for the trusted domestique in what was the final day in the mountains.
"I just couldn't breathe and my heart rate went super high and that was it," the Brit said. "It's frustrating really, I couldn't even stay in the bunch."
"It's frustrating, really," he continued. "You want to do your job."
Meantime, the remarkable run of from of Greg Van Avermaet continued with the Belgian securing his third top-five finish of the race, and his sixth podium in the US this month having previously competed at the Tour of Utah. Van Avermaet finished third in the sprint finish behind Sagan and second-placed Luka Mezgec (Argos-Shimano).
"I started my sprint at 200 meters to go," Van Avermaet said. "Sagan is a bit stronger and came over me. It's another good try, I think, and it's nice for me to be up there in the sprints. Plus, it has given me good motivation for the next races."
Van Avermaet said his main priority of the day was to assist van Garderen and Frank, ensuring the 15-man breakaway came back to the bunch.
"I tried to bring Tejay in a good and safe position to the finish," he said. "I think we did a really good job with the team. That was our first goal. Tejay is still in yellow without losing time."