Upgrades

Upgrading is something that many players neglect to do.  This is often since threats are on the table and you have to spend resources to get your tech up and have a standing army.  However, can upgrades sometimes be a game decision?

Like most of these questions, it really depends on the situation, and I think I'll break this down into the 3 matchups that occur, and make a special mention if it applies to a particular build for that matchup.

ZvZ

I might as well start off with the most important match to get upgrades in.  ZvZ is often a roach v baneling battle, but every once in a while you get some great hydra/roach compositions duking it out.  In this case, get your upgrades ASAP!  Tech up to your roach warren and get them first to hold off early rushes (with your queen as well) and right about the time you are dropping a hydra den, get dual evo chambers and start pumping ranged and melee attacks.  I recently saw a replay where an 8 roach 6 hydra army took out a 12 roach 10 hydra army, and still had 3 roaches and a hydra left in the aftermath.  Upgrades > troop count for this case.  Of course a 2000 mineral NOT upgraded army will devour a 1000 mineral army upgraded army any day of the week.

ZvT

This is probably the hardest matchup to write for since there will always be an argument for and against upgrades.  In my opinion, ground carapace upgrades and air attack upgrades are the way to go.  Against mech builds, your ground troops aren't going to be all that effective against leap frogging tanks, but at least if you have some armor you can get to "ground zero" next to tanks and have the friendly fire being.  Against the bio ball upgrades are less important since they shell out damage so quickly, but I say ground armor upgrades are still effective.  If switching to brood lords, go for the ground attack upgrades as broodlings will benefit from them.  Air attack is nice if heavy muta (my personal favorite strategy) since they can pick off stray units more easily and do some tactical strikes against key buildings if need be.

ZvP

I haven't played too many protoss players where an upgrade was a make or break decision.  Hydras deal fairly well with all the gateway units, so I usually go for ranged attack upgrades when I can.  Once collosi hit the field, no amount of armor is saving you from those beams so I would stick with attack and stay aggressive in the early going.

Swarm on!