[tialaramex]

This is sometimes called the game's "meta" but it's very unclear how much of this is real and how much is basically just fashion.

Some good but not quite star quality players like Ketroc deliberately ignore the meta. Ketroc plays with loads of Ravens, he did this when people said Ravens were strong but hard to use, he still did it when the accepted wisdom was that they were now useless, and last time I looked he was still at it after yet further balance changes to SC2. How he uses them changes, but he likes Ravens and they never stopped being viable.

Games like Chess have meta too. A year ago humans believed that materiel was essential and strong position made up only for small differences like losing a pawn or two. Then Google's Alpha Zero AI says hold my beer, sacrificing loads of my pieces for positional advantage is fine, because I can use that advantage to pin your extra pieces and still mate you away.

[s_m_t]

Sorry, a bit of ambiguity here, I was talking about SC:BW, as the paper is also concerned.

I think that SC2 and BW differ in this respect because SC2 has been constantly updated throughout its competitions to make more strategies and units viable. The last balance patch for BW was two years after release in 2001 (although a recent bug fix is said to have slightly buffed valkryies, there is some dispute about whether this actually pans out in practice but I haven't looked into it).