Nobody is going to call Taylor Kemp the best or even most important piece in D.C. United's attack. He wasn't last year - even acknowledging his six assists - and he's not going to be this year, either. Only in extraordinary circumstances will a fullback be the first name you think of when talking about a team's attack.
Kemp's not the team's best or most important defender. Again, fullbacks typically aren't the first name on that list, at least not on good teams with center backs that are worth a damn. (That said, Kemp's defense improved by leaps and bounds last year, especially in 1v1 situations against the fast and skillful players who had left him in their dust previously. Even if he's not winning tackles, he's finding ways to prevent them from running unimpeded into the box or to send in unchallenged crosses. This is good thing.)
He is, however, the best left fullback at Ben Olsen's disposal, and his play has been something of a barometer of the team's fortunes over the last year.
By that I mean that when Shooter is able to get forward regularly and find himself with the ball in some space in the attacking third, it's probably because things are going well for D.C. United. When Kemp is pinned back, it's usually because the team as a whole can't hold onto the ball. It's not that Kemp's play dictates how United will play, but he's probably the best spot on the field to check and see pretty quickly how the game is going for los Capitalinos.
So that's what I mean by bellwether. When I say "So goes Kemp, so go we all," it's less because United are following him and more that where and how he plays is a direct reflection on the success of the team as a whole. When the system is working and Kemp is able to get into the attack, where his left foot has to be registered as a deadly weapon in 13 states, he's the guy that 83% of B&RU readers wanted to see return after last season. When possession breaks down time after time, though, he's much less comfortable - and so are a lot of fans, if the comments on that season review piece from December are any indication.