They graduated a lot. It takes a little time to get in playoff form. Lake Taylor, Manchester, Highland Springs, Hermitage and Thomas Dale are great teams and nobody claims Bird should beat them more often than not if they played this year, but nobody denies that Bird was in the game with all these teams and capable of beating them if a ball bounced right here or there. If you're good enough to play with those three teams, then you're a threat in the playoffs.
Unless you're truly special (see Dinwiddie last year for an example), you're going to have to win those games in the playoffs a time or two, and Bird has been lucky (blessed? determined?) so far to win those games in the playoffs the past three years.
24-20 over Hermitage when they were down 20-10 with 4 minutes to play started off their run.
7-3 win over Salem last year with a blocked field goal with around 3 minutes to play setting up their only score.
14-10 win over Ocean Lakes, where one long run in the first half and a great defensive play in the final two minutes got it done.
35-28 over an amazing Briar Woods team that had them down 15 at the half, and which required their QB to set a passing record with a broken collarbone to get the win.
The magic looked like it was continuing when they got the Hail Mary against Dale, but Lake Taylor had the heart to stop them short by a few inches on 4th down to seal up the win and Manchester had Mary on their side. Was Bird really any worse in those two games than they were in those previous close playoff wins? No. It's a game of inches and they had a nice streak of winning some by inches.
Bird's magic returned with a 25-23 win on a last minute field goal against Highland Springs. Did that field goal prove Bird was better? What if it bounced off the upright and didn't go through? Is that enough to say one team is better than the other? Nope. I used to tell people when they got mad at me over the Gilliam Ratings that they read too much into close wins and losses.