Brian Bruney was never really very good.
A career ERA of 4.52, K/BB rate of 1.35, and FIP of 4.73 is not the line of a good pitcher. Even in 2006, his beast season, he was extremely lucky. His worse-than-average 4.57 xFIP doesn't jive with his pristine 0.87 ERA, which is better explained by his absurdly high 97.9% of runners left on base in that year.
But whatever luck Bruney had ran out in a big way this year. Bruney's LOB% plummeted to 58.8%, his BABIP shot up to 0.372 (perhaps attributable to a slower fastball), and he was dishing out the walks left and right. Though Bruney's failures may be partly attributable to Stan Kasten's preseason castration of the middle reliever, even if Bruney were performing up to his career standards, he would simply be average.
Bruney's replacement, Drew Storen, has great minor league statistics and should be an improvement over Bruney. And if the bullpen continues to perform at its current pace - which implies performances much better than the career averages of its members - then Bruney's demotion should be a real boost for the Nationals.
I wouldn't bet on that happening, though.
It hurts me to say it, but expect the Nationals' bullpen to begin blowing games at its normal pace soon. When your bullpen is composed of very average players, average performance is what you should expect from your bullpen. Unfortunately for Bruney, his bad luck had to come at a time when fortune was taking a liking to his teammates, making Bruney, by comparison, look awful.
Sorry about that, Brian. Oh, and if I were you, I wouldn't place any bets anytime soon.