If you take that verse in context (Ecclesiastes 9), you'll see that Solomon is lamenting the fact that "time and chance" ultimately negate any individual merit (strength and swiftness) in the long run (since in the end we all die). The swiftest runner could trip or pull a muscle, and in the chaos of battle anything could happen. Take David Vs. Goliath. Solomon's own father defeated the stronger opponent. Other circumstances of chance can change the tides of war, too.

It's interesting to note that after Solomon became wise, he began to fall into something of an existential angst. I think that shows in this passage.