I love Matt Kemp, and listed him earlier in the season as a guy that will move back into the first round this year.
While it's easy for us to say that regression will occur, I'm not so sure. He's increased his flyball percentages and line drive rates, and most importantly the HR/FB rates have been on a yearly increase.
I have him on pace for a 35/45 season. If you think you can take the short term hit on power, or even get a serviceable bat trading him, and deal with the loss of stolen bases, then perhaps now's the time to try and do a deal like you said for an Andrew McCutchen and tier two starter.
You do lose a bit in power but perhaps not as much as you think.
Keeper League:
F) N.Backstrom, E.Malkin, V.Lecavalier, P.Mueller, A.Mcdonald, B.Boyes, A.Hemsky, S.Horcoff, K.Turris, D.Jeffrey, M.Perreault, C.O'Reilly, S.Upshall, M.Erat, S.Gagne, D.Legwand D) S.Souray, M.Streit, A.Babchuk, T.Gilbert, I.Cole, J.Hillen, M.Methot G) B.Elliott, S.Varlamov, C.Ward, J.Reimer P) N.Kadri, E.Kuznetsov, S.Shirokov, V.Tarasenko, J.Blum, OEL, J.Moore, O.Pavelec