Evolution takes a long time, but it's not necessarily gradual. One theory is that it happens in bursts; a species will stay the same for thousands of generations and then, over a much shorter period of time, experience a dramatic change. I think LaRussa and Eckersley in 1988 was one of those leaps. I'd say that, other than the DH, the ninth-inning specialist is the worst innovation I've seen in my years of watching baseball, which dates back to 1971.