Out of the top 6 only Arsenal and Chelsea made very good transfers last season
Sanchez
Fabregas
Costa
I would say that West Ham (Creswell and Valencia), Swansea (Sigurdson, Gomis and Fabianski), Everton (Lukaku), Southampton (Foster, Bertrand, Tadic, Pelle) did well and got good value.
The biggest losers for me were Liverpool, United and Hull!
Looking back at our transfers I think our business was OK
Mangala - good signing
Fernando - good signing
Lampard - good signing as just loan
Caballero - poor signing as takes one of the foreign spots and a Home Grown option would make more sense
Sagna - poor signing
Zucchini - unsure