I don't see anything surprising in this in fact it's predictable. First, McVay's cute quippy "explanation" aside--c'mon this is easy to see through.

TG has an arthritic knee. They wore him out last year. With major wear and tear an arthritic knee flares up (pain, swelling). A back can run with an arthritic knee IF it's managed. (A few weeks back there was a great interview with backs who also ran on arthritic knees, like Brian Westbrook. They talked about how it's managed.)

To manage him they scaled back his runs early in the season and saved him for the end of the season. The opposite of last year. The alternative is to over-use him and risk another flare-up, in which case he would have to be sidelined. The alternative then is to over-use him earlier in the season and risk losing him at the end of the season.

As for McVay's "explanations" I take that this way. Gurley does not want the knee talked about. The Rams are respecting that. It puts McVay in a somewhat awkward position but by now this "gee whiz I forgot about TG in the flow of the game" routine is clearly and transparently just an obvious cover story. By sticking to it to the point where it is even ludicrous, he just ends up looking like the coach who respects his player's wish to not talk about this, and it even becomes kind of funny. The fact that it's OBVIOUSLY not true makes it funny, really.

Arthritic knee. Managed his carries. That explanation covers every detail of what we DO know...AND any other explanation makes no sense.

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