My understanding is that the primary concerns immediately post-exercise are rehydration and restoration of glycogen stores, not protein.
Protein is useful post-exercise, but not if it's at the expense of the other two.
A small amount of protein will benefit carbohydrate absorption post-exercise, but so will increasing the amount and frequency of carb consumption.
The greater the degree of dehydration, the greater the fluid requirement. However, since dehydration causes a delay in gastric emptying, dehydrated athletes should be wary of taking in large volumes of fluid at one time. Instead, athletes should continually sip on fluids until they feel the dehydration resolving itself. For athletes involved in sequential day practices or competition, the immediate postexercise period is an opportunity to replenish depleted glycogen stores. The enzyme glycogen synthetase is highest when glycogen stores are most depleted. This enzyme converts glucose to glycogen, so consuming high-carbohydrate foods, as tolerated, immediately after exercise is a desirable practice. This practice is inhibited by the relative degree of dehydration experienced by the athlete. The greater the degree of dehydration, the smaller the amount of food tolerated (because of delayed gastric emptying).
Despite the increased protein requirement for athletes, most athletes consume much more protein (from food alone) than they require. A look at the protein content of some commonly consumed foods demonstrates this point.
Protein utilization is, to a large degree, a function of total energy intake adequacy. An inadequate total energy intake forces athletes to burn protein for energy, making less protein available for other critical functions.
There is a common misunderstanding that extra protein intake alone will support a larger muscle mass, and this theory is the main rationale for the large protein intakes seen in many athletes. In fact, additional total calories are required to support a larger muscle mass, and protein should constitute the same relative proportion of the extra calories consumed. For instance, if a 75-kilogram (165 pound) man wishes to increase his muscle mass by 3 kilograms (6.6 pounds), he would need to consume approximately 1.5 additional grams of protein for each kilogram of muscle mass desired. This amounts to only 4.5 grams of additional protein to support the larger muscle mass. By contrast, 30 grams per kilogram of additional carbohydrate, or 90 grams of additional carbohydrate in total, is required to support the larger muscle mass. Here is the total additional caloric requirement represented by the additional muscle:
4.5 grams protein × 4 calories per gram = 18 kilocalories from protein
90 grams carbohydrate × 4 calories per gram = 360 kilocalories from carbohydrate
Total additional calories = 378 calories per day above current requirements to support a 3-kilogram increase in muscle mass
Of course, this athlete would also need to stimulate muscle enlargement by undertaking the appropriate strength-building exercises. Otherwise, the extra calories would manifest themselves as stored fat rather than additional muscle. It is likely that the large amount of protein consumed by so many athletes represents the extra calories they require to maintain or enlarge the muscle mass. Although it is certainly possible to use protein as a primary energy source, it is not the most desirable source because of the nitrogenous wastes produced with protein oxidation.
...quotes from: http://www.healthline.com/hlbook/adv...orts-nutrition
...and chocolate milk here (note, not chocolate protein shake, as wabbit implied):