if you adopt LoC as productivity metric then this is what you will get: first 6 months: more LoC => more features next 6 months: more LoC => less features next

if you adopt LoC as productivity metric then this is what you will get: first 6 months: more LoC => more features next 6 months: more LoC => less features next 6 months: more LoC => 1 feature next 6 months: more LoC => some existing features not working well and so on because a new feature is not only adding code but changing code. and the more code you have the more you have to change it.