What would be really interesting is putting a similar smart AI on the tanks, which could make decisions like shooting at the highest concentration of zerglings instead of the closest one, or holding its fire if one lone zergling is in range, but a clump of them is about to enter range.
Human players already do both optimizations with widow mines, which are a unit that takes several seconds to prepare its shot so it's feasible to retarget. It's not feasible for humans to do this with tanks though as they fire immediately and automatically.
You could even see counterevolution as two AI algorithms become better at predicting what the other will do.
(it's also possible the system is receiving information directly from the game engine, but it's definitely possible to figure this out from nothing but the information on screen)
The top contestants were employing strategies that required APM an order of magnitude higher than what players could do. For example, in brood war, SCVs can repair any Terran building or vehicle but it is not worth the effort to repair goliaths or tanks for a player.
However, the AI could easily manage repairing it's tanks which makes the Terran army much more cost effective.
In SCII there is auto repair and other improved UX that probably limit the ability of novel strategies like repairing vehicles.