Fans and players can blame Valentine until they are blue in the face, we've been down that road before.   Bobby Valentine is not the reason why the Red Sox are under .500 this season.   
The sole problem can be blamed on poor execution both offensivley, defensively and pitching.

1.   OFFENSIVELY:    Sure the team is at the top in runs scored this season, but too many times they go lackluster too (case in point last night).    Injuries can be partially to blame for that, but even so they have had enough capable players to score 4 or 5 runs yet only manage 1 or 2.     They have had so many big time run scoring games it kind of scues their overall numbers to make them look better than they really are.    They have scored 9 and lost or actually needed 10 or more to win how many times?

2.    DEFENSIVELY:   Spare parts playing more than they should in Aviles, Sweeney, Punto,  etc.     Blame the injury bug on this part.   But its not been the defense that has hurt them so much as the pitching.

3.    PITCHING:   Just horrendous from opening day when you start with a bullpen that blew up just about every night in April.     Horrible seasons by Beckett (still horrible) and Lester (better of late) accompanied by a slow/injury start for Bucholtz, better than expected pitching from the #4 and 5 starters yet now innings pitched taking its toll.    Nothing again from Dice K and Lackey both hurt.     Bailey we finally get to see now in mid August.

Valentine needs to bring in his own staff if he stays.     Time for a new pitchng coach, they held on to McClure after last September's pitching meltdown yet let the manager go?
Ban injured non productive/"cancers" like Lackey from clubhouse and dugout while rehabbing.
Either trade Beckett via waivers or just shut him down and get him on a conditioning program and go with some youth.    Cannot count on him performing if they think they DO have a run in them the rest of the way.  
If they really want to try for a run then do this:
Try to get Polanco from Philly for the rest of the season to play 3rd.
and get Ortiz back in lineup and offense should be fine.
If Lester has finally turned the corner, once again either trade or bench Beckett and find a 3rd starter to go along with Lester, Bucholtz, Morales, Doubrant and use Cook earlier in games when either Morales or Doubrant are shaky by 4th or 5th inning.

If hope is lost this season:   Play the farm and see what we have for next year.