I don't have any inside information. This isn't a list of necessarily credible candidates. It's spitballin' time.
Frank Cignetti (QB, St. Louis Rams)
Cignetti cracked into the NFL in 1999 with the Kansas City Chiefs and has bounced around as either an offensive coordinator or QB coach at both the NFL and college ranks since. He's been the Rams' QB coach since Fisher's first season in 2012.
Ray Sherman (WR, St. Louis Rams)
Sherman has been coaching for 39 years having broken into the NFL in 1988 with the Houston Oilers. The pedigree is there, having held single-season OC duties three teams with the New York Jets (1994), Pittsburgh Steelers (1998) and Minnesota Vikings (1999).
Rob Boras (TE, St. Louis Rams)
Boras is perhaps the most notable rising star on the Rams' staff now in his 11th year coaching at the NFL level. Previous tight end coaching stints for Chicago and Jacksonville preceded his current position with the Rams. This may be the most likely in-house option:
As for offensive coordinator, no names just yet but if -- IF -- Rams decide to go in house, a name to keep an eye on is TE coach Rob Boras.— Nick Wagoner (@nwagoner) January 7, 2015
Marc Trestman (ex-HC, Chicago Bears)
Trestman was hailed as an offensive guru having grown up in the NFL ranks in the '80s and '90s. Following a stint with Montreal in the CFL, the Bears gave him a shot in 2013. Now ousted since, he's one of the more popular options for teams looking for an offensive mind.
Dirk Koetter (ex-OC, Atlanta Falcons)
Koetter made some early rounds so the Rams may be late on this one. He'd be an obvious legitimate candidate if he isn't scooped up to quickly having helmed both the Jaguars' and Falcons' offenses the last eight years.
Greg Roman (OC, San Francisco 49ers)
Roman's in the same boat having attracted multiple suitors already this offseason.
Aaron Kromer (ex-OC, Chicago Bears)
Kromer's career was sizzling after breaking into the NFL in 2001 and being a part of some explosive offenses in New Orleans from 2008 to 2012. With Trestman's ouster, some of that falls on Kromer. If he doesn't get an OC gig this offseason, he'll find another gig quickly.
Rob Chudzinski (Spec. Asst., Indianapolis Colts)
A serious up-and-comer whose shining star plunked into the sea after a single season in Cleveland in 2013. Chud was the TE coach with the San Diego Chargers in 2005 and 2006 under then-HC Marty Schottenheimer...full circle life, this.
Marty Mornhinweg (OC, New York Jets)
He's just so NFL. If I were betting, this would probably be my money on the line as of right now.
Josh McDaniels (OC, New England Patriots)
HAHAHAHAHAHAHAHAHA. Oh God wait...no, please don't.
Rhett Lashlee (OC/QB, Auburn Tigers)
This one may not be as outlandish as you might think. The fit wouldn't be perfect as Auburn runs way more option looks than is acceptable in the NFL (read: more than 0 option looks), but it could be an out-of-the-box hire for an Auburn-friendly Rams GM in Les Snead who would certainly feel familiar with Greg Robinson at OT and Tre Mason as his running back.
Art Briles (HC, Baylor Bears)
This has no shot at happening as (a) Briles has no reason to not take a head coaching gig, (b) Baylor is becoming one of the nation's best football programs and (c) this would be a lot of fun and the Rams kill fun with fire, bleach and sin.
Lane Kiffin (OC, Alabama Crimson Tide)
I'm not sure how Saban and Kiffin didn't come to blows during a game this year. I just can't see him wanting to stick around there even if it did work. And it did.
The Holy Grail
Dana Holgorsen (HC, West Virginia Mountaineers)
Holgo was a top OC at Houston and Oklahoma St. before taking over for Bill Stewart at WVU. There, he turned his Geno Smith-Tavon Austin-Stedman Bailey triumvirate into a whirlwind offensive powerhouse. I couldn't endorse this more.