Why is the Nydus Worm underused? - Page 17

I'll be looking at Game #4 of the Winter Assembly Finals
http://www.gamereplays.org/starcraft2/portals.php?show=news&news_id=869070

Skip ahead to 10:30 and lets look at Stephano's situation.
-Spire just finished
-He's making 7 mutalisks
-He has 1k/160 in the bank and he invests 100 of that into air upgrade 1 + floats gas + starts melee upgrade 1 later. It's entirely reasonable to say at this point Stephano should have 150/200 spare at this point by not floating minerals (a mistake he made) and his ability to defend would be unchanged (as he spends gas on a 2nd upgrade before the next muta he makes is completed, so in total he spent 250 gas on stuff that doesn't help until much much later).

Thus at this point, 10:30 exactly. Stephano could make a Nydus Worm with absolutely no risk of anything different happening over the next 50s compared to what he chose to do (air attack +1). Much later his air attack would be delayed, but I'm going to show how much he could have gained via Nydus play.

Now lets go ahead to 11:10. Where we have this:


Why is this important, lets look at our situation.

• Nydus canal would be done instantly at this moment if build when air attack was researched..
  
• Polt has a 3rd that's open, but defended.
  
• Stephano has just moved mutalisks in and the base is relatively undefended
  
• Polt's army is far away from the base. How far?
  
  • There's 6s before Polt moves any marines
    
  • The closest marines are moved back at 11:36 and arrive at the mineral line at 11:50 that's 14 seconds.
    
  • The area centered on the picture is about 4 seconds further away than that.
    
  
  That's a total (not counting reaction time) of 18seconds.
  

That means Polt would have 2 seconds to react to even have a non-0% chance to get to worm before it emerged, which is a far cry from the 6s it took him to react and it assumes he runs right for the worm rather than to protect his SCVs (which Stephano can follow with mutas if Polt moves by rather than a-moves).

His 13 marines available dealing 10.5dps would take 2 seconds to kill the worm which is enough time for 4 banelings to emerge. Yet this assumes he stims his marines a 2nd time giving them only 25hp to survive the mutalisks that could be there. Otherwise he has 4s to get units out free of charge.
Of course this ignores any marines that die from the 7 mutalisks that can attack them (each muta volley would just kill one marine outright I believe if he doesn't re-stim).

Likewise he also has to choose between protecting the SCVs, or attacking the worm unless he pulls the SCVs TO the worm which he could do, but that puts them right in the line of fire for the mutas and since we know the worm is almost sure to survive it's a big risk.
Now SCV's do 2.67dps to the worm so their dps isn't that significant and if they're pulled immediately to the worm there are 7 mutas there getting to take free shots on them for 14s (when the marines arrive). Even if the worm was killed in this way the SCV loss is a huge hit to Polt well worth the worm's cost (and canal, but Stephano gets to keep that regardless).
We know pulling the SCVs to hit the worm is a huge risk as Stephano because Stephano has banelings. If they are first out of the worm they will detonate and annhilate large scv #s, something that would be a huge blow to Polt.

Additional army is, at this point, 15-20s away and there's only a minimal force on the 3rd that Stephano can scout/spot. Unless you sac the SCVs, this worm is completing. Even that nearby tank is about 12s away + 4s unsiege and if it moves before the marines arrive it's vulnerable to the mutas (plus the tank costs more than the worm).
If Stephano put his canal at his nat (towards the ramp down) lings could be 5s away from both the nydus AND Polt's 3rd by standing near the Xel'Naga, which means that up until 5s left on the worm Stephano can threaten the 3rd if additional forces are pulled back
to prepare for the worm finishing. Since those marines are about 25s-30s away from the nydus worm, that gives Stephano a huge timing advantage. Polt has to pull them RIGHT AWAY if he wants to defend a full on nydus in his base, but Stephano can wait 15s to decide if he wants to hit the 3rd or hit the main.

The tanks are there, but keep in mind that all Stephano needs to do to win is kill the marines really (Polt would be defenseless vs the mutalisks). None of them can get there in time to kill the worm before units emerge either with 4s to unsiege and their slow movespeed.

Stephano has enough units at this point to kill Polt so long as polt can't make use of a defensive position (sieged up siege tanks). Since we're forcing Polt to pull back to the main if we hit there, his tanks won't be sieged for most of the battle.

What if Polt's units were better positioned? Well what would that look like. Would it be any better to Stephano's option of pulling his muta's back and hitting else where sans worm? I fail to see some magic configuration that Polt should have known to do that would be well equipped to handle this attack + the threat of a full frontal attack. Not to mention if Stephano was planning on this type of strategy he could easily scout the unit positioning with a ling poke ahead of time. By seeing the # of marines gathered near the 3rd + the fact that Polt has a 3rd, he would know the main is relatively undefended.

Now you might also say, "It's a risk! What about late game" Well we know Stephano likes Ultras late game in many situations. Shakuras may not be the best map for late game nydus play, but we do know it's something that can be effective . So maybe he is delaying air attack or skipping it, but so long as he protects that canal he's setup late game to make better use of Ultras. So he can deal tons of damage now or if it doesn't pan out is setup to do well later with a nydus up.

So lets recap:

• Stephano could have made a Nydus Canal at no-risk to his immediate safety.
  
• Stephano could have made a worm right as he harasses with mutalisks with 0 risk to the mutas.
  
• Polt would have have almost 0 chance to kill the worm before at least 2-4 units emerge and have time to attack. With his actual reaction time it would be at least 12 units out of the worm before he even starts attacking it.
  
• Stephano had banelings that could almost instantly remove all threats on the worm, or at least force them to stop attacking the worm (never mind the mutas themselves)
  
• Without sieged siege tanks Stephano's army is superior.
  
• Polt's additional reinforcements aren't in range of the worm until 5-10s after it completes
  
• If Polt pulls back all units his 3rd is completely open (as is his natural). Yet Stephano doesn't need to commit to hitting the main vs 3rd until 5s before the worm finishes (10s after Polt has to pull back).
  

Conclusion/TL;DR
Thus I contend that I've shown a real world example with PRO players where a Nydus Worm would have offered a UNIQUE chance to win or gain an advantage that no other thing in the Zerg army could have done. This is the finals game of a big tournament that could have been won with a Nydus.

I don't think this is a unique situation either and I'd love to go through other games if people want me to. This isn't some convuluted situation either. Any time a T builds in this manner with a more reactionary muta defense, they're open to this type of timing attack, it's not something that happens every game (map matters a lot as other factors). Nor does it require much setup, the only demand is you delay air attack and instead make the canal.