No secret ingredient... unless you consider the mold, low RA (in H22 Pro Stocks a different layup and even lower RA), and the 16x19 string pattern with 8 Mains in the throat, special.
If I'm not wrong, it's basically Wilson's version of the Head Liquidmetal Radical Tour MP that Djokovic was playing with. I think the Head Liquidmetal Radical MP is a fantastic racquet as well (never played with the Tour version as they are rarer and I don't want to dish out big money for used ones).
With all of these racquets (H22, HLM RT MP, and HLM RMP), I think it's the mold design, lightweight/ high SW/ tighter string pattern combination that is what is special. They have excellent control, are able to deal with heavy shots and pace from the opponent, have great power in stock form, and can then easily be modified to personal specifications without becoming too heavy in static weight.
For the Pros, they have a racquet that already has a higher SW and great stability in stock form, so they can either leave the head alone and just modify the handle side to get their desired specs... or they need to add minimal weight to the head (for men to get their 350-360SW), and then add the weight to the handle (silicone, or silicone plus lead, etc) to get their desired static weight, balance, SW, TW, etc.
It basically provides many things that are desired by high-level players/ Pros in stock form and isn't too complicated to modify (if that's required). I think this was basically a lightweight solution to the PT57As/ PT630s. It provided the stability and comfort of the latter, in a low static weight package. With the PT630 you have a heavy racquet that is phenomenal if you can hit the smaller sweet spot, but any modifications to the head resulted in a very heavy racquet. Here, the Pros and high-level players (or those that can wield the racquet with its higher SW) were given a racquet that was light in static weight, stable, bigger SW (that could be made enormous with small mods), bigger TW (that again could be made rock solid with small mods), and a light static weight that could be used in stock or modified to a much more manageable static weight when finished. What resulted was a racquet that had a bigger sweet spot, similar or better stability, but was more adaptable to a range of static weights required by a larger range of players.
Hope that has answered your query.