Tony Romo, Dez Bryant and the rest of the Cowboys head into Sunday’s game against the Colts leading the NFC East and on the verge of a playoff berth. [...] he’s the one who’s likely to receive plenty of praise from fans if the Cowboys do return to the postseason for the first time since 2009. “I feel really good about where our coordinators are in running their different units and how our position coaches are coaching,” Garrett said. Coming off three consecutive 8-8 finishes, Dallas demoted defensive coordinator Monte Kiffin and removed Bill Callahan as play caller. [...] Scott Linehan calls plays (something Garrett used to do), helping turn running back DeMarco Murray into a star. Callahan, meanwhile, has thrived while focusing on what is probably the league’s top offensive line. New defensive coordinator Rod Marinelli has overseen significant improvement, while linebackers coach Matt Eberflus has produced a pretty good group despite the loss of Sean Lee and others to injury. In general, assistant coaches do not get a lot of publicity or kudos — this season, for the first time, the AP NFL awards will include one for top assistant — but Dallas’ group deserves both. Here’s a look at some other underappreciated — and overblown — aspects of the NFL: Presumably, Mario Williams & Co.