Without knowing how well Vikings LT Bryant McKinnie played last season, or knowing much at all about new VIkings LT Charlie Johnson, I can't say whether the switch from McKinnie to Johnson is a major blow.
But I'm really surprised at how outspoken his former teammates were by his sudden release. From ESPN:
I can't say for sure that no one was upset by the decision to release longtime left tackle Bryant McKinnie, who reported to training camp weighing nearly 400 pounds.
Here's what I can tell you, however: Some players would have been upset if the Vikings hadn't released McKinnie...
In the offseason, Winfield said, "guys do different things. Some guys relax, some guys travel. Some guys like to party. But you have to be disciplined. All you have to do is go work out, stay in some kind of shape, and perform."
While those words aren't overly harsh, I rarely see direct quotes like that about another player from anyone other than LB James Harrison.
I was really surprised initially by his release, but McKinnie has shown bad judgment in the past. Most recently when he got kicked off the Pro Bowl team.