Maybe I'm mistaken (sorry if that's the case), but I thought your view on Fowler is that he hurts his team more than he helps?
Now, if that's what you are saying, is it your belief that Fowler having a +20 goal differential during the last four seasons (including playoffs) is an anamoly, and that the luck will change any day now?
I hate using +/- because it's so dependent on the team you play on. An absolute train wreck of a team might not have a single plus player, even though their best defender might be better than the #7 on a championship squad, who might be +2 or +3 in the same stat.
That being said, Corsi is misconstrued and too many people recite stats off a page without knowing anything about the player. What does a bad CF% rating say? Does the player have missed assignments aplenty in his own end? Or does he continually make dumbass turnovers? (Exhibit A: Kevin Bieksa)
Now, there's a problem here as well: let's say that this horrible defender (cough cough Bieksa) is paired with a good player. This unnamed horrible player can't contribute to the transition game, he is constantly caught up the ice with his pants down on the rush back, he's a negative player offensively with only a decent slapshot to contribute to offensive zone play, and his defensive coverage is nothing short of horrible. Obviously he just might drag down his partner, right? His partner is good (albeit inconsistent at times) defensively, he's a fantastic skater and very good on the transition, and his offensive zone play is very good and is complemented with a much-improved shot. A solid #2.
Now, Fowler isn't a shutdown defender, regardless of what Boudreau tried to make him into. Throughout his career, he's shined his brightest in an offensive role. Though his offseason training and his changes to his playing style deserve much of the credit for this, his usage by RC is one of the big reasons he's having an offensive renaissance. He's seeing plenty of PP time, he's being more aggressive offensively, and he's been employed in a much more offensive role. He's not a shutdown defender, and trying to turn him into one is likely not going to aid his development any. He's not as bad defensively as people seem to think; from Lovejoy to Bieksa to now Vatanen, he's never been paired with defensive stalwarts. In fact, when he was paired with Manson, his Corsi stats looked a lot better. Now, Manson is a good #4 who has excelled as a complement to Lindholm, but he's not good enough where he can carry defenders. For Fowler's Corsi stats to jump up like they did with a legitimate shutdown DFD such as Manson means less that Manson is carrying the pairing than Fowler is finally playing with a good player. Fowler's now paired with Vatanen -- both OFDs who love to push the play. Fowler's offensive style has dominated over Vatanen and Vatanen is then being forced into a more defensive role where he's really struggled. (I might note that Vatanen has been mostly sheltered throughout his career yet stats say that he's better than Fowler who hasn't been sheltered at all over the past few years)
My verdict on Fowler: His defensive game isn't his strong suit. He's good there and he unfairly gets **** on due to having defensively lackluster partners, but he shines when he's able to move the puck up the ice and make things happen in the offensive zone, not when he's being coached into being a DFD while being paired with one of the worst players in the league. According to the metrics, Fowler is one of the best transitional defenders in the league, but this gets ignored in favor of more popular stats like Corsi which don't exactly portray him in an endearing light.
And my verdict on Corsi: Better used as a metric for evaluating line/team performance than for individual performance/skill. There's just too many independent variables in what affects the metric to use it reliably for an individual player. A player's chemistry with his partner/linemates, his partner's or linemates' talent, his usage (zone starts and strength of opposition), and the system in which he plays can all have profound affects on a player's Corsi rating, as well as several other variables. (such as coaching skill and the strength of the surrounding team) Attempting to use it as a tell-all for overall skill is like stepping into a poorly-insulated refrigerator and attempting to tell the temperature outside. You just can't do it because that darned refrigeration system is getting in the way and marring your results. If this poorly-illustrated example doesn't do the job for you, let me put it this way: all scientific experiments have a potential to fail if there are significant variables affecting it, which is why having a controlled environment for experiments you conduct is very important. Corsi is no different, but a controlled environment is unfortunately impossible. Now, if you're using Corsi for the evaluation of a line's
performance (not necessarily skill), you can eliminate the first two variables. Not enough to make it a tell-all, but no statistic is perfect. If you use Corsi for the evaluation of a team's performance, you can knock off usage for the most part, as well as obviously any negative or positive influences from overall team skill.