I think in 2011 the teams were also figuring out how to portfolio manage in the new slotting system, the balance of easy signs with risky upside. Merrero had an awful senior year but a terrific junior year. He went to a program with a really strong history of producing pros - including of course the Sun Devils' former undersized shortstop. I think they saw some projection, or at least a quick path to the bigs - they got neither. It's ok - 24th pick has a fairly low ROI to begin with.
The draft SEEMS like a roll of the dice, and in baseball the "sure thing rate" is lower than other sports. But the top of the draft is still a very good predictor of pro success. Note how Tampa's system took off as they drafted high year after year, and the rankings have slipped as guys have graduated as well as they have stopped picking at #1.