do n't derive from the screenplay , but rather the mediocre performances by most of the actors involved 
(ROOT (S (VP (VB do) (RB n't) (VP (VB derive) (PP (IN from) (NP (NP (DT the) (NN screenplay)) (, ,) (CC but) (ADVP (RB rather)) (NP (NP (DT the) (JJ mediocre) (NNS performances)) (PP (IN by) (NP (NP (JJS most)) (PP (IN of) (NP (NP (DT the) (NNS actors)) (VP (VBD involved)))))))))))))
(ROOT (S (VP (VB ) (RB ) (VP (VB ) (PP (IN ) (NP (NP (DT ) (NN )) (, ) (CC ) (ADVP (RB )) (NP (NP (DT ) (JJ ) (NNS )) (PP (IN ) (NP (NP (JJS )) (PP (IN ) (NP (NP (DT ) (NNS )) (VP (VBD )))))))))))))