The Ducks are winless in their first three games of the preseason.
The Sharks finished the night outshooting Anaheim 49-14.
Ryan Getzlaf scored a power-play goal for Anaheim.
The Sharks are 2-0 in the preseason.
The Ducks drew an unusual delay of game penalty at the start of the second period when they arrived late to the ice from the locker room and weren't prepared to start the period.
Andrew Murray's power-play goal at 18:15 of the third period made the score 5-1.
Mitchell's goal came on a power play at 17:25 of the second period, giving San Jose a 4-1 lead.
Anaheim made it 3-1 when Getzlaf scored 10 seconds into a power play at 14:56 of the second.
San Jose jumped out to a 2-0 lead late in the first period when Irwin and Boyle scored.
Irwin's score came on a power play at 15:21. The rookie defenseman was playing in his first NHL preseason game.
Boyle took a pass from Thornton and was quick to get set up and score with 1.4 seconds left in the period.
Notes: Sharks goalie Antti Niemi has yet to skate with the team after having a cyst removed last week. ... Last season's backup goalie, Antero Niittymaki, will be out 12 weeks after undergoing hip surgery earlier in the week.
|PPG - Matt Irwin (1) Slapshot - ASST: Mike Moore (1), Michal Handzus (1)|
1 - 0 SJS
|Dan Boyle (1) Slapshot - ASST: Joe Thornton (1), Joe Pavelski (1)|
2 - 0 SJS
|Douglas Murray (1) Wrist shot - ASST: Mike Moore (2), Joe Pavelski (2)|
3 - 0 SJS
|PPG - Ryan Getzlaf (1) Slapshot - ASST: Cam Fowler (1), Bryan Rodney (1)|
3 - 1 SJS
|PPG - Torrey Mitchell (1) Wrist shot - ASST: Michal Handzus (2), Brent Burns (1)|
4 - 1 SJS
|PPG - Andrew Murray (1) Backhand shot - ASST: Mike Moore (3)|
5 - 1 SJS
|Corey Perry Hooking - 2 min against Andrew Desjardins|
|Bobby Ryan Delay of game - 2 min|
|Sean Zimmerman Interference - 2 min against Michal Handzus|
|Matt Pelech Hooking - 2 min against Nicolas Deschamps|
|Cam Fowler Hooking - 2 min against Tommy Wingels|
|Andrew Gordon Interference on goalkeeper - 2 min against Thomas Greiss|
|Francois Beauchemin served by Bobby Ryan Boarding - 2 min against Tommy Wingels|
|Brandon Mashinter Fighting (maj) - 5 min against Francois Beauchemin|
|Francois Beauchemin Fighting (maj) - 5 min against Brandon Mashinter|
|Brian McGrattan Cross checking - 2 min against Brad Winchester|
|Brad Winchester Fighting (maj) - 5 min against Mark Bell|
|Mark Bell Fighting (maj) - 5 min against Brad Winchester|
|Mark Bell served by Bobby Ryan Cross checking - 2 min against Brad Winchester|