It's been some time since anyone furtively complained about Brent Burns playing defense on this website. "Move Brent Burns to forward" is a hill I died on last year and now they're starting to lump dirt on what's left of my decomposing body. This is good, of course, because Burns playing well defensively is good for the Sharks which is good for our constitution.
But let's not blow things out of proportion. Yes, Burns has made strides in his defensive game but the improvement of his plus-minus, which we're talking about for some reason, likely has more to do with his PDO than with his play. Let's start with the basics: PDO adds together on-ice save percentage and on-ice shooting percentage. That number usually rests around 100, although if we're talking about a team with very good goaltending or very good shooting you might see some fluctuation.
Burns PDO has, for most of this season, been very low. Below is a chart that looks at the fluctuation of his PDO since being moved to defense at the beginning of last season. It's a rolling average, which means the plots look at the previous 20 games.
This doesn't tell the whole story, of course. Maybe the Sharks are getting better shooting positions now that Burns is playing better or the opposition is getting worse looks for the same reason. Maybe! While anecdotal evidence and the eye test at least makes me feel that Burns' play has kept the opposition from generating many scoring chances...the numbers don't really back that up.
This chart only looks at even strength high-danger scoring chances against, scroll down to location data to read more about that. As far as stats go this is one of the better ways to grade Burns' defensive play and it's...well, it's not gotten better since the season started, really. That also applies to Burns' fenwick against per 60 minutes numbers.
Again, these numbers don't tell the whole story, but it's worth noting as a way of keeping the eye test in check. Yes, Burns has looked more confident on the puck and (in my opinion) has made better decisions in regards to pinching and shot selection. That hasn't exactly turned into better possession or scoring chance numbers for the Sharks, but if he continues to improve we might end up seeing that show up on the stat sheet (plus/minus doesn't count, I'm sorry).
I already mentioned the whole dead on a hill thing, but I do think Burns' offensive output mostly outweighs his defensive miscues. Similar (but nowhere near as good) to P.K. Subban, I think it's easy to focus on the mistakes instead of the positive contributions. Burns has been good for the Sharks and his booming shot is one of the best parts about watching San Jose play.