  We explore the implications of the observed low spin of GW150914 within the
context of stellar astrophysics and progenitor models. We conclude that many of
the recently proposed scenarios are in marked tension with this observation. We
derive a simple model for the observed spin in the case that the progenitor
system was a field binary composed of a black hole (BH) and a Wolf-Rayet star
and explore the implications of the observed spin for this model. The spin
observation allows us to place a lower limit for the delay time between the
formation of the BH+BH binary and the actual merger, $t_{\textrm{merge}}$. We
use typical values for these systems to derive
$t_{\textrm{merge}}\gtrsim10^{8}\,\textrm{yr}$, which proves to be an important
diagnostic for different progenitor models. We anticipate the next series of
events, and the associated spin parameters, will ultimately yield critical
constraints on formation scenarios and on stellar parameters describing the
late-stage evolution of massive stars.
