If you sound convincing, people will believe you.
Rex's strategy is genius. He said: "Being ranked 4th last year was a disappointment with this talent; we're going to be No. 1 in the league this year, no doubt." Or words to that effect.
That all sounds a lot better than "I'm going to take a great defense and make it below average. Confusion, lack of effort, and league leading, undisciplined, stupid penalties will be the hallmarks of my stamp on this team!"