Remember where we stood with Steve Birnbaum at this time last year? D.C. United had adroitly played Philadelphia and Vancouver off of each other to trade down, make some money, and still get the player they always wanted, but Birnbaum's 2014 preseason was making the decision look just a little bit iffy. He bore quite a bit of responsibility for two similar goals conceded in consecutive games, and with Jeff Parke in the fold one could be forgiven for wondering if United had overestimated the Cal product.
A year's a long time in soccer. Birnbaum is now a United mainstay in central defense, was arguably snubbed for the Rookie of the Year award, and has a USMNT cap to his name. You guys love him, and rightfully so. He's got all the athletic requirements one would want out of a center back, his decision-making is comparable to someone a few years older than him, and he has a knack for keeping the game simple for himself and for others. He's also the right sort of partner for Boswell, who is adept at stepping into the midfield to break attacks up early but needs a faster partner to cover in behind him.
Still, the dynamics of every soccer team change from season to season, and with any player anywhere there are reasons to be concerned. In Birnbaum's case, it's less about him being satisfied - it doesn't seem like he's the sort of player to coast on past achievement - and more about potential obstacles that may come up this year that weren't in place in the past.
We should start with a reminder that Birnbaum hasn't even played full MLS season yet. Parke started the first 13 games of 2014 for United. 21 games is more or less the length of a college season, which is something Birnbaum is plenty familiar with. Can he maintain his form over the grind of a season that could stretch into December and feature more than 50 games? Obviously he won't start every game, but maintaining one's mental sharpness over that much time and with the amount of travel involved is a test Birnbaum hasn't encountered yet.
Actually, Birnbaum's season may even be longer than it seems. His USMNT call-up means he's already a month into his 2015 season. Throw in the very strong evidence that Jurgen Klinsmann's training sessions are grinding players into dust rather than setting them up for a long season, and one has to wonder how well he can hold up physically. Birnbaum need look no further than his USMNT center back partner Matt Besler for evidence of what happens to a player who has been worn out by overuse. Ben Olsen's modifications to training and regular off-days kept United healthy in 2015, but he can't control what happens when a player is subjected to grueling two- or three-a-days elsewhere.
There's also the possibly anecdotal issue with coaching. Enzo Concina - now an assistant coach to Frank Yallop in Montreal - had a lot to do with United's impressive defensive organization in 2014. The principles he brought to the team will surely be remembered by the other coaches and the players, but it's still a potential issue at the back.
None of this should indicate much pessimism for Birnbaum. To steal a phrase from Olsen himself, the kid's a stud. I think it's still fair for fans to expect Birnbaum to keep getting better given his hunger to learn, his age, and his still-untapped potential. However, we also can't expect that it's just going to be easy.