Fabian Zetterlund and Luke Kunin scored for the Sharks (6-12-5), who have lost three in a row and six of seven (1-3-3). Blackwood made 27 saves.
"With the group we have, you're never going to be perfect. You're always going to be learning how to do some things, especially as we get later into the season," San Jose forward Macklin Celebrini said. "But I mean, we've done it before, and I think we know what to do and just need to execute."
The Sharks honored former longtime captain Joe Thornton in a pre-game ceremony, retiring his No. 19 jersey.
"It's disappointing, right? You wish you could find a way to win that one for Jumbo," Sharks coach Ryan Warsofsky said. "[It was a] big night for the organization. It's frustrating."
Celebrini is living with Thornton this season, making tonight's ceremony extra special.
"This weekend was really special. You could tell how emotional he was and the family was. I've only known him for a couple of months, but it's emotional for me watching that, seeing how much I meant to him and his family," Celebrini said. "How others and his teammates spoke about him and the praise they gave him fits everything I know about him and everything I've heard about him."