The idea he would go on to espouse is that football teams never remain the same in terms of performance and ability. They either improve through hard work and preparation or they worsen through apathy and ignorance. But they are never static, they never stay the same.
I think this idea is applicable to many areas of life. A 'plateau' is never really possible. Once you have plateaued, and you cease to grow or improve, you are actually declining. Consider education or a skill set for a hobby or a relationship; if these things aren't growing or improving or expanding they are actually diminishing.
In A Body of Divinity, Thomas Watson applies this principle to spiritual growth as well. Considering this type of growth is 'organic', I think there is some truth to the ideas he shares here:
Such as do not grow in grace—decay in grace. "Not to go forward in the Christian life is to turn back," Bernard. There is no standing still in piety—either we go forward or backward. If faith does not grow, unbelief will. If heavenly-mindedness does not grow, covetousness will. A man who does not increase his stock, diminishes it. Just so, if you do not improve your stock of grace, your stock will decay. The angels on Jacob's ladder were either ascending or descending. Just so, if you do not ascend in true religion, you descend. (276)
Let us be encouraged to keep ascending, to keep growing, to keep going forward, to keep pressing on. We must. Because we don't remain the same.