He did not blame Army at all. He said, "“A big part of why we didn’t make the playoffs (in 2017-18) was a lack of goal-scoring, and a lot of the summer was built around trying to bring some people in who could help score goals,” Yeo said. “But I got away from my usual plan in training camp. We spent a lot of time trying to create more offense, then obviously the defensive game wasn’t as strong." No mention of Armstrong.
It was JR, summarizing things who said "perhaps with input from Armstrong". I am more disappointed with the writing...well, not disappointed, as it is JR after all. I dislike that style of interview reporting where the author puts much of it in his own words. If Yeo blamed Armstrong, there would be no "Perhaps". He would either believe Armstrong pressured him for more offense, or not believe it. Either way, there would be no perhaps because he was there. That is JR insinuating his own thoughts into the interview, which is terrible journalism.