"I feel better," was all Bourque said to the media after the skate ahead of a game against the Carolina Hurricanes.
"We're seeing progress," he said. "In both cases, they're on the right track."
Bourque, who has missed 17 games, returned to practice after getting a green light from team doctors on March 20 only to suffer a setback a few days later. He recently visited Atlanta to see concussion specialist Ted Carrick, who treated Pittsburgh star Sidney Crosby.
Diaz, who has missed 16 games, has not yet resumed skating.
Forward Ryan White, who has missed three games with an ankle injury, also skated and said he expects to return soon.
Defenceman Tomas Kaberle, who cleared waivers over the weekend, was also on the ice.