Players to have an +8 fWAR over the last 5 years
2013
Trout - 10.4 WAR
2012
Trout - 10.0 WAR
2011
Ellsbury - 9.1 WAR
Kemp - 8.4 WAR
2010
Hamilton - 8.4 WAR
2009
Pujols - 8.7 WAR
Zobrist 8.5 WAR
Utley - 8.0 WAR
2008
Pujols - 8.6 WAR
Utley - 8.0 WAR
2007
AROD - 9.6 WAR
Wright - 8.4 WAR
Magglio Ordonez - 8.0 WAR
2006
Pujols - 8.2 WAR
2005
AROD - 8.8 WAR
Pujols, Utley, Magglio, AROD, and Hamilton all had sharp declines, it's conceivable that Kemp could too.