There are a few people you can blame for this issue. That being said, if you're putting together that list, MacTavish absolutely belongs on it.
This team has an image problem to fight around the league, and it comes from the perception of bumbling management. And you don't improve such a perception by snap firing a coach over Skype, and hiring a coach who flames out as badly as Dallas Eakins did.
Or by mishandling players who've gone on to better careers elsewhere (Dubnyk, Perron, etc.).
Or by trading useful players off the roster before he had players who could step in for them (Horcoff, Hemsky, Smid).
Or by bringing in a player to be captain before he knew if this guy would even be accepted in the room (Ference).
Or by playing hardball with decent players (Petry) while he backed up the Brinks truck for not so decent players (Nikitin).
Or blatantly over valuing certain players to the point of being a laughing stock (Schultz).
Or the fact that he's changed 70% of the roster and the team is now winning even less than before.
Is there enough there to give MacTavish some blame for the "loser" image problem the Oilers have?
Is he getting too much blame for things that happened when he wasn't here? Maybe he's getting blamed for the Lowe/Tambellini snowball effect, but that's life when you're a GM. He's seen as Lowe's boy, which means he's getting no breaks. If that's too tough for him he shouldn't have taken the job. You're making an executive level salary and you're expected to produce. Coming in and making things worse, then blaming them on your predecessor, is a weak, weak move.
Even if you don't think it's fair, recall what MacTavish said when he fired Krueger. It's not about being fair.