There were really two main things I was replying to:
Therefore, subs have only 75% of the effectiveness that destroyers do, making the destroyers a better buy.
I think that is not really a correct assessment. The most destroyers I would ever want is 1, and even that is questionable. The reason is that the early strike ability of the sub is very over-rated. With a single opposing btl, you need 4sub before your early hit is mathematically significant. Even then, opposing subs can be taken as casualties and still fire, so you’re not gaining much - odds are that sub would have died in the first round anyway. There is almost no large naval battle where the early sub shot will be a big difference maker. But if my opponent has 10 subs and I have fewer than 2btl, I’d want 1des. That’s about the only time.
So yes, infantry suck for attacking.
I think Switch has shown that inf are about as good as tanks $ for $. After spending 60 IPCs, the tanks have only managed to kill one additional unit.
This all comes back to the three tactical fundamentals:
Count - Who has more units? This is usually the most basic and most important assessment. Look at the R1 Baltic battle if Germany buys a single tra: you’d have 2ftr 1bmr vs. 2subs 2tra 1des. The count wins even though the oPunch is 10 and the dPunch is 5. The oPunch is DOUBLE the dPunch, but because the dCount (5) is almost double the oCount (3), the defender has a better chance to win the battle.
Punch - Who has the best chance to inflict the most damage per round? Punch is found by adding the “hits-on” values for units. So on offense 3inf 1tnk has oPunch = 6; on defense that same group has dPunch = 9. Punch is related to count, but not directly. Obviously four attacking bombers bring more punch than four attacking inf (oPunches = 16 vs 4, counts = 4 vs 4). You want punch; but take care of count first.
Skew - The strongest tactical groups match high values and low values to make use of “fodder”. You don’t want “even” groups of all 2s or all 4s - a skewed mix of 2s and 4s is better. So Switch is on the mark when he says you need a mix of units to be effective.
If you really want some exciting math, check out the Caspian Sub Policy Paper #05 about tactics. It covers what Switch was demonstrating as well as a few other tricks like Count Equivalents.
http://games.groups.yahoo.com/group/Caspian_Sub/
Peace