A parade to the penalty box put the Bruins in a hole out of which they could not climb and they dropped a 3-1 decision to the Sharks in San Jose on Sunday.

The B’s took six minors and it was Macklin Celebrini’s power-play goal in the second period that stood up as the game-winner.

The Bruins went into the third period down 2-0 but got back into the game with a goal from — who else? — Morgan Geekie. With the return of Elias Lindholm after nearly a month out, coach Marco Sturm tried some new line combinations with David Pastrnak on a unit with Pavel Zacha and Marat Khusnutdinov and Geekie with Elias Lindholm and Alex Steeves.

But with the offense stagnant, he put Geekie and Pastrnak back together with Zacha in the third period and the line responded with a dominant shift, finished off by Geekie’s 17th of the year. Pastrnak took the puck behind the net and made a terrific backhand pass to Geekie for the goal from the top of the crease at 10:02 of the third.

The B’s continued to pressure but gave up an empty-netter with 1:07 left. Nikita Zadorov circled back into the Boston zone and signaled for Jeremy Swayman to head to the bench. But then the defenseman’s pass from his own zone intended for Geekie at the red line was picked off by Celebrini and the Sharks were able to attack with Collin Graf finally putting it into the empty net.

The B’s found themselves down by a goal at 15:53 of the first period shortly after they killed off their second penalty. Shakir Mukhamadullin was allowed too much time and space, giving him a chance to move down to the right circle and his wrister ramped up off of Mikey Eyssimont’s stick over Swayman’s shoulder.

The B’s, outshot 12-10 in the first, had one power play in the opening period, with which they did nothing.

The second period saw the B’s come out better, led by the physicality of the third line of Tanner Jeannot-Frader Minten-Mark Kastelic again. They had a better power play but they could not score. And Pastrnak also forced Yaroslav Askarov to make an excellent save on a one-timer from the left circle.

But all those good vibes went down the drain when the Sharks cashed in on a power play at 11:45. The momentum shifted just before the PP when Dmitry Orlov upended Sean Kuraly in the Sharks’ zone on a hit that Kuraly felt was too low. As Kuraly jawed with Orlov, Ty Dellandrea attacked the Boston zone with speed and forced Jonathan Aspirot to trip him.

On the man advantage, Celebrini used a screen to beat Swayman to make it 2-0.

The B’s penchant for penalties nearly could have cost them more later in the period. After Aspirot took another tripping penalty, Hampus Lindholm was called for roughing off the faceoff, giving the Sharks a 5-on-3 for 1:50, the seventh time the B’s have been down two men this season.

But the B’s managed to kill off the first penalty and then William Eklund wiped out the remaining nine seconds with a questionable holding call on Zadorov. The B’s couldn’t cash in on the first part of the PP but started the third period with 45 seconds left on the advantage. That went by the wayside, too.