The Arizona Diamondbacks reportedly heard offers for Robbie Ray. Bob Levey/Getty Images

While unsigned star sluggers Bryce Harper and Manny Machado remain the hot topic of baseball's offseason, recent trade rumors have surfaced involving some notable starting pitchers.

Arizona Diamondbacks left-hander Robbie Ray has reportedly drawn trade interest from teams. According to Nick Cafardo of the Boston Globe, the Houston Astros and Philadelphia Phillies "are very interested" in the 27-year-old.

Ray in 2018 had a 3.93 earned-run average over 123.2 innings and a WHIP of 1.35. His best season was in 2017 when he had a 2.89 ERA over 162 innings.

Ray, who is under team control for the next two seasons, is expected to earn just over $6 million in 2019.

The Diamondbacks have drawn attention in the offseason after trading star first baseman Paul Goldschmidt to the St. Louis Cardinals. There had also been reports that Arizona would consider a trade for veteran Zack Greinke.

Cafardo also noted that the Toronto Blue Jays have listened to offers for Marcus Stroman and listed the San Diego Padres, Atlanta Braves, Texas Rangers and Phillies as teams that could deal for him.

The 27-year-old was limited to just 19 starts in 2018 due to a shoulder injury. His numbers were down from a stellar 2017, posting just a 4-9 record with a 5.54 ERA last season.

Stroman, who made $6.5 million in 2018, can become a free agent after the 2020 season. In 2017, the right-hander had a 3.09 ERA over 201 innings.

Meanwhile, John Morosi of reported that the Milwaukee Brewers have had talks with the New York Yankees over Sonny Gray. Morosi also noted that the Cincinnati Reds had also shown interest in the right-hander but the talks faded after acquiring starters Alex Wood and Tanner Roark.

Gray, 29, struggled in 2018, posting just a 4.90 ERA over 130.1 innings.