There are two ways to look at Sharks defenseman Brent Burns lining up at forward against the Blues on Tuesday night. The pessimist asks, did the Sharks really trade Devin Setoguchi, Charlie Coyle and a first round pick to Minnesota for a third line forward, when Burns was supposed to be, essentially, the long term replacement for Dan Boyle as the team’s number one defenseman? The optimist would say the Sharks’ defense hasn’t been the reason San Jose has just two regulation wins in its last 20 games, and even though Burns is healthy, now is not the time to tinker with the blue line corps. That includes defenseman Matt Irwin. The 25-year-old rookie seems to have secured a place in the lineup, at least for now. He’s played in every game since he was recalled on Feb. 26, and has done an admirable job at getting shots through from the point, something that the Sharks had been struggling with until recently. On Sunday in Colorado, Irwin recorded a whopping eight shots on goal against the Avalanche, just the 10th time in franchise history a defenseman has recorded that many. Boyle has done it four times (Tom Pederson, 2, Rob Blake, Christian Ehrhoff and Gary Suter are the others).