[Next_rim]

you see what i mean...

I do see what you mean, but it's hardly applicable to starcraft for two reasons. First, probe count (and thus income) beyond 70 makes your army weak. Therefore, there is a theoretical "maximum" income you can and should have. Second, any macro game involves a 3rd base somewhere around 14 mins, if not earlier. Author recommends to use games that are 15+ minutes long for this very reason.

Now, if you look at difference between a 15 min game on 3 bases and 999 min game (still on 3 mining bases), the only factor that affects income is game actions - harass and more expansions. If you slip on expansions, or lose probes to harass, or lose a base, average income will plummit, signalling worse macro. Although it might not be directly connected to player macroing badly, maybe he was just out of position to defend a base, but a pro supposedly will get back on track very soon compared to lower league. That's why the author states that it's important to use longer games, since it is more likely the game will feature 3 mining bases.