There is an argument that post-workout nutrition is all about precision; too much protein and you will induce metabolic acidosis, thereby blunting any anabolic response and elevating catabolic hormones. If too "complex" a source of protein is used, synthesis will not be fast enough to make the difference.
A good post workout drink should also contain easily absorbed di and tripeptide amino acids to maximize the anabolic drive process, rapidly restoring positive nitrogen balance. Also high concentrations of Branched Chain Amino Acids (BCAAs) to replenish a depleted amino acid pool and delay fatigue.
Sounds complex huh? Well that’s the optimum solution, and you hope that the manufacturer of the off the shelf product will have sorted all of this out for you. On the other hand, will the “optimum” solution make a noticeable difference to you over what you are suggesting? I would actually guess not, but the only advise is to give it a go and see how you feel.