How do you coach players to TANK.
I think you would have players demanding trades.
If I were orchestrating a team tanking I would have a heavy dose of young players, with every veteran being someone who was completely hard working and did what the coaches asked of him. Someone who could help the locker room work on honing their craft without loafing or doing foolish things off the field. The veterans role would be to create fellow players who lived for the team.
Then the vast majority of guys on my roster would be rookies or players with less than 3 years experience. So a few of those guys would possess a lot of talent, and many of them would be flawed or raw guys, like OL with sloppy technique, WR's who needed to work on their route running, etc. Then, I would focus hard on the fundamentals. Some of those sloppy/raw kids would learn and begin to blossom into solid role players. Those guys I'd keep the following year. The rest would be shed in the offseason. So the tank year would be used to hunt for and develop gems, all the time realizing that we were going to fail far more than we were going to succeed in this search. But, we will likely find/develop some gems, whether they're potentials sleeper stars or just solid role players, we're likely to find a few.
In the draft I would look at trading for future picks, preferably of equal or higher value. If we're tanking, we're OK with delaying gratification for that talent. In fact, we'd rather stack them later into the team so that the stars could grow together as our team rises from the ashes after tanking.
Football is primarily about knowing the fundamentals, consistently executing those fundamentals, and filling your roles reliably. Yes, it requires stupendous athletic ability, but there's a LOT more people who have that ability out of the NFL than there are in the NFL reliably doing it. Every year each team probably cuts 5 to 10 guys who have special athletic gifts, but who are more track stars or workout warriors than football players. When we tank, we're looking to take players with talent and give lots of them chances. So many of them will fail that it almost guarantees we effectively tank. But, the few that succeed will be hidden gems that help us rise above the mediocrity in which we so often find ourselves mired.