Dan Duquette may be facing uncharted territory in his Orioles’ career.

His club, languishing under .500 and in fourth place in the AL East, could be a seller at the July 31 non-waiver trade deadline – even though he talked publicly Saturday about looking to improve his rotation for a stretch run.

Veterans such as Zach Britton, Brad Brach, Darren O’Day, Welington Castillo and Seth Smith have been made available on the trade market as the Orioles look to replenish their farm system.

And that’s a position Duquette has never been in since taking over as the Orioles’ executive vice president of baseball operations in November 2011. The Orioles have had a .500 or better record during each of his five seasons at the helm, and Duquette’s usual approach has been to acquire veterans, not trade them away.

So, if the Orioles intend to be sellers this time around, what kinds of trades can fans expect to see from Duquette? Historically, how has he fared when swapping veterans for youngsters? We know his “buyer” deals for the Orioles haven’t worked out too well, but what about the flip side?

Let’s take a look at some of his notable sell-off trades from his previous GM stints in Montreal and Boston.

MONTREAL EXPOS TENURE (1991-1993)

Duquette’s experience as a seller began almost as soon as he got his first MLB general manager gig, taking over the perpetually cash-strapped Expos in September 1991. He faced the ongoing task of trying to deal the club’s veterans before they inevitably left for bigger bucks in free agency.

Nov. 25, 1991: 1B Andres Galarraga to St. Louis Cardinals for RHP Ken Hill

Galarraga had been a quality first baseman for the Expos for eight seasons. But the 30-year-old “Big Cat” was a year away from free agency and coming off a poor 1991 season when Duquette struck his first major trade as GM, swapping Galarraga straight-up for Hill, a 26-year-old righty.

The trade was a steal for the Expos. Hill put up three strong seasons atop the Montreal rotation, going 41-21 with a 3.04 ERA during that span and finishing as NL Cy Young runner-up in 1994. Meanwhile, Galarraga suffered through one ineffective, injury-plagued season with the Cardinals before leaving as a free agent, though he later resurrected his career in Colorado.

Dec. 9, 1991: Traded RHP Barry Jones to Philadelphia Phillies for C Darrin Fletcher

Jones, a veteran reliever, spent just one season with the Expos, tying for the NL lead with 77 appearances and picking up 13 saves while posting a 3.35 ERA. Duquette struck while the iron was hot, swapping the 28-year-old for Fletcher, 25.

Fletcher found a home with the Expos, becoming their starting catcher for the next six years, while Jones pitched so poorly for the Phillies that they released him before he’d spent a full season there. Again, Duquette came out on top in this swap.

Dec. 11, 1991: Traded OF Dave Martinez, OF Willie Greene and LHP Scott Ruskin to Cincinnati Reds for RHP John Wetteland and RHP Bill Risley

The main piece of this deal from the Expos was Martinez, 27, a veteran outfielder who’d been with Montreal since 1988 and was a year from free agency. Duquette also threw in 28-year-old reliever Ruskin and prospect Greene.

Duquette struck gold in Wetteland, who had spent three seasons as an ineffective swing man with the Los Angeles Dodgers. The Expos converted him to full-time relief and reaped the rewards. Wetteland emerged as the club’s closer, racking up 105 saves in three years while pitching to a 2.32 ERA.

Dec. 24, 1992: IF Tim Wallach to Los Angeles Dodgers for IF Tim Barker

Duquette’s relationship with Wallach was among the lowlights of his Expos’ tenure. Wallach, a popular Expo, was a five-time All-Star and three-time Gold Glove third baseman during his excellent 13-year Montreal career. But Wallach bristled when Duquette and company asked him to move to first base before the ’92 season. The experiment lasted only a few months, but created ill will between Wallach and the Expos.

Duquette unceremoniously traded him after that season for Barker, a Baltimore-born infielder who never made it out of the minor leagues. It was an uninspiring return for one of the best players in club history.

Nov. 19, 1993: 2B Delino DeShields to Dodgers for RHP Pedro Martinez

Eleven months after the failed Wallach trade, Duquette swung another deal with the Dodgers — and it became one of the most successful swaps in recent baseball history. In exchange for the speedy DeShields, 24, Duquette acquired a scrawny 22-year-old whom the Dodgers thought would never succeed as a starter because of his 5-foot-11 frame.

Nearly 25 years later, Martinez is enshrined in Cooperstown. (Spoiler: DeShields is not.) His Hall of Fame career track began with the Expos. It was in Montreal in 1997 that Martinez won the first of his three career Cy Young awards, going 17-8 while leading the league in ERA (1.90), complete games (13), WHIP (0.932) and strikeout rate (11.4).

On a side note, Duquette traded for Martinez a second time, acquiring him from Montreal for pitchers Carl Pavano and Tony Armas in a “buy” trade for the Red Sox in November, 1997.

BOSTON RED SOX TENURE (1994-2002)

After taking over the Red Sox in 1994, Duquette didn’t have much need to trade away veterans; the deep-pocketed club had a winning record during seven of his nine years – technically, seven of eight since he joined the 1994 Red Sox (54-61) in late January while the 1994 Expos he built and left that January were 74-40 — and was usually in a position to buy instead of sell. However, Duquette did make a few sell-off trades in 1996 and 1997, when the Red Sox finished in third and fourth place, respectively.

July 30, 1996: LHP Jamie Moyer to Seattle Mariners for OF Darren Bragg

Yes, Duquette dealt away Moyer, who ended up being one of the most remarkable success stories of his generation. But it’s tough to blame Duquette for not foreseeing that. At the time of the trade, Moyer was a 33-year-old journeyman who had a career 4.58 ERA for five teams, so few took notice when the Sox swapped him for a 26-year-old outfielder in Bragg.

Little did Duquette — or anyone — expect that Moyer would win 201 games from that point forward, scoffing in the face of Father Time and pitching until he was 49. Moyer’s major league career, in fact, ended eight years later than Bragg’s did.

Jan. 27, 1997: OF Jose Canseco to Oakland Athletics for RHP John Wasdin

Canseco muddled through injuries during his two-year stint with the Red Sox, but was productive when healthy, batting .298 with a .960 OPS, 52 home runs and 163 RBIs from 1995 to 1996. Duquette dealt Canseco back to his original team, the Athletics, for the 24-year-old Wasdin, who was Oakland’s first-round pick in the 1993 draft.

Wasdin didn’t pan out for the Red Sox, posting a 4.66 ERA in parts of four seasons, and he pitched for five clubs after that, including the Orioles in 2001. Wasdin, though, clearly made a favorable impression on Duquette during their Boston days. The Orioles hired him as their minor league pitching coordinator this season.

July 31, 1997: RHP Heathcliff Slocumb to Mariners for RHP Derek Lowe and C Jason Varitek

You’d think the DeShields-for-Pedro trade would go into the books as the best trade of Duquette’s career. Four years later, though, he may have topped it, pulling off another incredibly lopsided heist that changed the direction of his franchise.

The Red Sox, sitting 17.5 games back at the trade deadline, had little use for a closer — especially an underachieving, 31-year-old closer, Slocumb, who had 17 saves but a 5.79 ERA. The Mariners, desperate for bullpen help, agreed to send rookie righty Lowe, 24, and minor league catcher Varitek, 25, in exchange.

The rest is history. Lowe spent the next eight seasons in Boston as both a starter and a closer, racking up 42 saves in 2000 and a 21-win campaign two years later. He also won the clinching game of the 2004 World Series that snapped Boston’s 86-year championship drought. Varitek (pictured above), meanwhile, emerged as one of baseball’s best catchers and the captain of the Red Sox, for whom he spent his entire 15-year career.

Another Orioles’ tie-in here: The Boston scout that recommended Lowe and Varitek from the Mariners’ system was Gary Rajsich, whom Duquette hired in 2011 to be the Orioles’ scouting director.

As for Slocumb? He went 2-9 with a 4.97 ERA in parts of two seasons for the Mariners, and was out of baseball three years after the trade.