SANTA CLARA, Calif. — Mike Martz hardly seems like a coach scorned.

The 49ers' offensive coordinator wasn't chosen to fill the job opening created Monday by the firing of Mike Nolan, Martz's good friend and fellow NFL coaching lifer. Just seven games after Martz joined Nolan in San Francisco to fix the league's worst offense, Martz's boss is now Mike Singletary, the Hall of Fame linebacker who has six years of coaching experience — none as a coordinator or head coach.

Martz's two-decade NFL resume is highlighted by a mostly successful six-year run as the St. Louis Rams' head coach, and he has said he hopes to run his own team again. Many people — some inside the 49ers' locker room — wondered whether Martz would be bitter, surprised or disappointed.

He's none of the above, Martz insisted today in his usual quiet, serious tones.

"I came here because of Mike Nolan, and I think that Mike Singletary deserves this opportunity," Martz said. "I didn't come here with any kind of thought (to become the head coach), nor did it pass my mind. I love what I'm doing, and that's why I'm here, and this is what I continue doing well. I've kind of had my moments in that respect, and it's time for all of us to get behind Mike and help him any way we can."

Martz's best moments in St. Louis were awfully good. After moving up to the top job from offensive coordinator following the Rams' Super Bowl victory in early 2000, Martz went 51-29 in his first five seasons with St. Louis, winning another NFC title along the way.

But his coaching star darkened after a dismal final year, during which he missed 11 games with a heart ailment and feuded with the front office. He then spent two frustrating seasons as the Detroit Lions' offensive coordinator before joining San Francisco last January.

Martz declined to express an opinion about Nolan's firing, saying, "Those are all things that, for me, are off limits."

But Martz confirmed his job hasn't changed a bit with the transition up top before Sunday's home game against the Seattle Seahawks (1-5), the final opponent for San Francisco (2-5) before its bye.

Nolan essentially allowed Martz to do whatever he wanted with the offense, and Singletary has pledged to do the same. Martz and Singletary don't know each other very well, since they rarely had occasion to speak to each other before Nolan's firing, but Singletary knows that'll change soon.

"I'm going to stay the heck out of the way and let Mike do his job," Singletary said Wednesday. "I think he's a great coach, and I feel very fortunate to have him."

Martz has made clear progress with an offense that ranked last in the NFL in several key categories last season. Running back Frank Gore is off to a remarkable year, leading the league in total yards from scrimmage until the New York Giants shut him down last week, while veteran receiver Isaac Bruce and rookie Josh Morgan both have been solid.

"Coach Martz is doing a great job," Gore said. "We're way better prepared this year. He's changed the whole way of doing it around here, and we're a lot better team with him running the offense."

But there are still plenty of problems with an offense built around first-year starter J.T. O'Sullivan, who has been sacked 29 times while throwing 10 interceptions and fumbling nine times. George Warhop, who coached Nolan's struggling offensive line for 3 1/2 years, was fired along with Nolan and replaced by Chris Foerster, who joined the staff last winter to share the job with Warhop.

Learning Martz's intricate offense requires time and repetition, yet he acknowledges his new players aren't picking up the details as quickly as he prefers.

"We've had so many missed opportunities this season, so many of them, and these guys know that," Martz said.

The 49ers' misses are "way more than I'm used to," he continued. "The plays that we just normally make out here (on the practice field), we just sometimes don't make them (in games). They're learning."

Among the plays that stick out in Martz's mind is a picture-perfect screen pass he called against Philadelphia two weeks ago. Martz tricked the entire Eagles defense onto the other side of the field, leaving tight end Vernon Davis and three lineman alone for a walk into the end zone that would have put the 49ers up by 13 points late in the third quarter — but O'Sullivan and Davis couldn't connect on a short pass.

San Francisco then gave up 23 unanswered points in the fourth quarter, losing by 14.

"These guys spend so much time in preparation, and when things come out in the game just the way you hoped they would, you have to make all those plays, 100 percent of the time," Martz said. "You cannot miss one of them. Unfortunately, we've got a whole drawer full of those."