The NFL could always count on its assistant coaches to show up for work no matter how rocky labor relations became between the league and its players.
That could be changing.
The NFL Coaches Association, upset about benefits changes and the manner in which the league implemented those changes, is considering unionizing.
The association sent a letter Tuesday to its team representatives and NFL head coaches apprising them of the development.
"The owners exercised some of their options when they took back our standardized health care, our pensions and rule of 75, in addition to putting lockout clauses in your contracts," read the letter, a copy of which ESPN.com obtained Thursday. "The owners also asked you to be supportive of them in their CBA battles with the players; yet we have no say in their fight!"
The rule of 75 allowed coaches to take early retirement when their age and years of service added up to that number. The league stopped requiring teams to offer that option for coaches who do not yet qualify, one of several moves the NFLCA views as a threat to coaches' livelihood.
A league spokesman said federal law made benefits portable and the NFL merely gave teams more flexibility by offering their own benefit options, and that 21 of 32 teams still live by the rule of 75.
Eleven teams have opted out of the NFL pension plan since the league stopped requiring teams to participate, and some have offered substitute plans the NFLCA considers substandard. The change came after deteriorating market conditions cost teams money as they complied with federal laws requiring increased funding levels.
"They took the pension away with no forewarning whatsoever," said NFLCA executive director Larry Kennan, a former assistant coach. "They expect us to like the lockout clauses and not complain when they try to do away with the antitrust laws. We don't understand. All we have said is, 'Treat us with respect and dignity because we treat the game with respect and we want you to treat us the same,' and they haven't in any of us."
Tensions between owners and assistant coaches also rose when the NFLCA filed an amicus brief supporting American Needle in its landmark antitrust case against the NFL. A league victory in the case would establish the NFL as a single entity, not a collection of 32 competing teams. Legal experts say that outcome could prevent players, coaches or anyone else from proving or even levying charges of collusion.
"Several owners have really attacked the coaches on their staff and want to know why we are siding against the NFL in this American Needle case," Kennan said. "It makes no sense for us to do anything else."
The NFLCA letter to coaches says the association needs to "explore the possibility of becoming a union" through education.
Labor laws allow "employees" to unionize while preventing "supervisors" from going that route. Coaches from other leagues have not unionized, so there is no precedent for defining terms, but head coaches and coordinators might more readily qualify as supervisors -- defined in part as those able to independently hire, transfer, suspend, lay off, recall, promote, discharge, assign, reward or discipline employees.
"What the younger generation of coaches has to accept as it goes forward is that the rules can change and they can change on the run," said one veteran NFL assistant coach who requested anonymity for fear of backlash from ownership. "There is not the defined certainty you had before. I have seen a lot of change. None until recently has affected coaching as these last changes have, as people have started to draw the battle lines in terms of negotiations."
Veteran Indianapolis Colts coaches Howard Mudd and Tom Moore protested the pension changes last season by retiring and taking lump-sum payouts on their pensions. They then returned as consultants.
Mudd, a former Pro Bowl guard for the San Francisco 49ers, retired for good after the season. He thinks assistant coaches are increasingly at risk because too many are willing to ignore labor rollbacks while mistakenly thinking they'll become the next hot young assistant to become a head coach.
Salaries for some coaches have also risen to a level where apathy has become an affordable option, at least in the short term.
"Until that class of people gets together, then the owners are going to keep stripping away more and more," Mudd said. "To me, the potential is there for a salary cap for coaches -- not negotiated. Or they may say teams can have only so many coaches. I don't know what they are going to do."
Mike Sando covers the NFC West for ESPN.com.