What a weird discussion between
Ulvenvald mysteries and
evolutionary leap.
Ulvenvald mysteries can't compete with evo leap in terms of raw mana efficiency. Even in those mana constrained scenarios, evo leap performs better, because it requires less overall mana investment to function. The fact that you might occasionally waste a mana with evo leap by holding a green up, doesn't negate this.
Mysteries, however, is probably better at generating raw card advantage in a long game, unfortunately, there are not a lot of green midrange decks that are going to be natively excited about such a slow, purely card advantage focused gameplan, and the 1/1 bodies it generates to impact the board (while perhaps fine for retail draft or sealed) don't create the sort of meaningful board presence those decks want.
Tireless tracker is a variant much more in line with midrange strategies: a meaningful board presence that generates value while negating removal.
Mysteries seems like a
great card for retail limited, where format inefficiencies can allow very slow, but creature filled decks, that want chump blockers, and which can be focused on such a purely card advantage focused plan. There just isn't a great role for that sort of card in most cubes (though possibly still a more fringe role), and a lot of the stupid stuff you could do with the card, is negated by it not triggering on token deaths. Most people are probably better off just running tracker.