One gets the impression that the editors of L used the good stuff from the W and substituted their own, much better material when they encountered some of the bad stuff.
( One ( ( ( gets ( the impression ) ) ( that ( ( ( the editors ) ( of L ) ) ( ( ( ( used ( the ( good stuff ) ) ) ( from ( the W ) ) ) and ) ( substituted ( ( their ( own ( , ( ( much better ) material ) ) ) ) ( when ( they ( encountered ( some ( of ( the ( bad stuff ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP One)) (VP (VBZ gets) (NP (DT the) (NN impression)) (SBAR (IN that) (S (NP (NP (DT the) (NNS editors)) (PP (IN of) (NP (NNP L)))) (VP (VP (VBD used) (NP (DT the) (JJ good) (NN stuff)) (PP (IN from) (NP (DT the) (NNP W)))) (CC and) (VP (VBN substituted) (NP (NP (PRP$ their) (JJ own) (, ,) (ADJP (RB much) (JJR better)) (NN material)) (SBAR (WHADVP (WRB when)) (S (NP (PRP they)) (VP (VBD encountered) (NP (NP (DT some)) (PP (IN of) (NP (DT the) (JJ bad) (NN stuff))))))))))))) (. .)))
it appears that good aspects of W were taken and added to other excellent material by the editors. 
( it ( ( appears ( that ( ( ( good aspects ) ( of W ) ) ( were ( ( ( taken and ) added ) ( to ( ( other ( excellent material ) ) ( by ( the editors ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP it)) (VP (VBZ appears) (SBAR (IN that) (S (NP (NP (JJ good) (NNS aspects)) (PP (IN of) (NP (NNP W)))) (VP (VBD were) (VP (VBN taken) (CC and) (VBN added) (PP (TO to) (NP (NP (JJ other) (JJ excellent) (NN material)) (PP (IN by) (NP (DT the) (NNS editors)))))))))) (. .)))