It’s unfortunate that good touch percentages aren’t more widely disseminated. It’s far more helpful to determine who actually are the superior blockers than something like blocks per set. Middles are impacting the game in almost every rally, yet usually get reduced to something as small as 1.2 blocks per set - really almost a pointless statistic.
I agree with your overall point that GT% is better than blocks/set, but I still think there are issues with the GT% statistic. Colvin may actually get similar or better touches than Allick, but Allick's number is better because Nebraska had the best team defense in the country and were able to convert more of those touches into digs/attacks.
A few months ago, I tried to find a better way to determine blocking effectiveness based solely on numbers from a standard box score. In this hypothetical,
Team A averaged 1.89 Blocks/set
Team B averaged 1.77 Blocks/set
Conventional wisdom (just looking at B/Set) would indicate that Team A was the better stuff-blocking team. However, Team B's opponents were only taking 33.3 Attacks per set while Team A's opponents were taking 37.5 Attacks per set. Also, some of those attacks become general attack errors that weren't blocked. Maybe you could argue that attack errors are influenced by the block, but I chose to exclude those in the formula.
Again, just using the information in a standard NCAA box score, the formula that seems to work the best to determine the better stuff-blocking teams is:
Total Blocks / (Opponent's Total Attacks - (Opponent's Attack Errors - Total Blocks)) = TotalBlock%
or
TB / (OppTA - (OppAE - TB)) = TB%
Someone smarter than me can probably figure out a better/easier way to make that calculation. From the example before, Team B became the better stuff-blocking team by generating a stuff block on 5.99% of their opponents' "non-error" attacks while Team A only generated a stuff block on 5.62% of their opponents' "non-error" attacks, despite having a better B/Set number.
This is relatively common sense, but it also illustrates why Digs/set is a pretty poor way to determine how good a team's defense is. Team A averaged 17.1 Digs/set while Team B only averaged 14.6 Digs/set. Most good teams terminate at a higher level and their opponents take far fewer swings. A better team statistic than Digs/set would probably be:
Digs / (OppTA - OppAE) = Dig%
or just use OppHit% (it was the exact same for both Team A and Team B in this example).
Sorry for the irrelevant tangent, and any problems with the formatting that made this hard to follow.