Indeed, using the 17 percent margin of error, Xander Bogaerts' current fWAR of 3.2 could be as high as 3.744 or as low as 2.656.
If the 17 percent margin of error applies equally to Baseball Reference's WAR, Bogaerts' current bWAR of 2.1 could be as high as 2.457 or as low as 1.743.
Decent discussion.