After tearing an abdominal muscle against Tommy Haas in a first-round loss in the Shanghai Masters that prematurely shut down his tennis season in early October, the 6-6 American again is ripping deliveries.
But he's playing it safe by uncorking 130-mph serves only once or twice a week.
After a disappointing season marked by injuries, off-court distractions and bouts of mental fatigue, Querrey can't afford to hold back much longer. There is no time to waste.
"I kind of feel that my career is halfway done," the 26-year-old said in a recent phone interview.
Querrey's first half has been solid but somewhat short of the elite potential he demonstrated early on.
"He came out as a young kid with a lot of expectations, got to the top 20 pretty quickly and struggled with the pressure of thinking he could do much better without putting in the nine yards," said David Nainkin, his coach since 2009. "I think he's learned that it's going to take a little more."
Indeed, after establishing himself as a top-20 player in two of the last three years, Querrey backpedaled in 2013. He didn't reach a tournament final and failed to advance past the third round in a Grand Slam tournament for the third year in a row.
The Southern California native enters the 2014 season at No.46, his lowest year-end ranking since 2007 (notwithstanding 2011, when he had right elbow surgery).
Still, among the thinning ranks of American men with double-digit rankings on the ATP Tour, Querrey remains the second-highest-ranked Yank behind No.14 John Isner.
When he opens his 2014 season this month in Brisbane, Querrey should be fresh. For a month this past fall, he pulled the plug on tennis. He didn't hit. He didn't train.
"I literally did nothing," he said. "It was nice to regroup and come home and not think about tennis for a little bit."
That luxury never lasts long, and Querrey said he had been training hard since early November in Carson, Calif., with other American players such as Jack Sock, Steve Johnson and Donald Young.
"Mentally he could be stronger in big moments," ESPN commentator Darren Cahill said.
Locating a consistent joie de vivre in the peripatetic lifestyle of professional tennis has proved elusive for the laid-back, happy-go-lucky Querrey, who early in his career once showed up for a match with a gaping hole in his shoe.
In 2010, when Querrey won a career-high four titles and rose to No.17 in the rankings, he admitted after a first-round loss in the French Open that he had tanked portions of the match and just wanted to fly home.
In 2013, he came out of the gate with decent showings in the Australian Open (third round) and in Masters 1,000 events in Indian Wells, Calif., and Key Biscayne, Fla. (back-to-back fourth-round appearances).
"I wasn't really enjoying it as much as I should have. I got into a little rut," Querrey said.
"I'm not exactly sure what the right word is," he added, saying he was tired and homesick.
Injuries in the spring and summer didn't help. Querrey was slowed by a chest muscle strain and right elbow tendinitis, but he also missed events during the summer for personal reasons.
Asked about those absences, Querrey said: "I'm no longer engaged. I'll tell you that."
Querrey explained that the biggest distraction was splitting up with his fiancée, Emily McPherson. He said it took a toll on his tennis, especially during the summer.
He partially blamed his second-round loss in the U.S. Open to 63rd-ranked Adrian Mannarino of France to his poor mind-set. "Mentally I don't think I was all there."
Both Querrey and Nainkin see plenty of pavement ahead to return to elite status.
The aging men's tour has numerous examples of players pushing 30 or more with success, among them No. 3 David Ferrer, No. 6 Roger Federer, and No. 12 Tommy Haas. All three are past 31.
He has the weapons, too, among them one of the bigger serves and forehands on tour.
Querrey said his biggest frustration in 2013 was his overall inconsistency, especially in smaller 500- and 250-level events. By eliminating those seven to 10 losses, improving his forehand and second serve and playing more aggressively in tight moments, he is confident he can rejoin the sport's upper echelons. "If I fine-tune everything just a little bit, not even a lot, I can jump into the top 15," he said.
Cahill disagrees. He says Querrey, who has not reached the quarterfinals of a Grand Slam, needs to focus on the sport's biggest stages. "His expectations are not huge going into majors," Cahill said. "They sort of need to be the other way around."
Querrey said he intends to focus more on personal satisfaction than pure performance as he rounds into the second half of his tennis career.
"The only thing I want is to enjoy playing tournaments and the process more than I did in the first half," he said. "I don't necessarily care what I'm ranked or if I win more tournaments or what, I just want to have fun and really enjoy it because this is something not a lot of people get to do. It's something really exciting and something I should enjoy every time out there."
His decision to hire Nainkin away from the USTA to be his exclusive coach should pay dividends.
For the last year and a half, Querrey shared Nainkin with fellow American Sloane Stephens – an unusual cross-gender arrangement.
"I want someone holding me accountable, pushing me," explained Querrey. "I just want to give myself the chance to see how good I can get and the only way is to have someone with me full time."
With his diminished ranking, Querrey is unlikely to be seeded at January's Australian Open.
"Sam is going to come out hopefully hot in the early part of the year," Davis Cup captain Jim Courier said in a conference call this month while discussing Isner and Querrey. "Hopefully they can tie everything up together and play at the level that they're capable of. If they do, they're both top-10 players."