The 31-year-old Goldschmidt has spent his entire eight-year MLB career with the D-backs.
Goldy is coming off another strong campaign, as he slashed .290/.389/.533 with 33 home runs, 83 RBI and 95 runs scored in 2018. He's hit .290 or better in each of the past six seasons, and he hasn't hit worse than .286 in a full MLB campaign.
Also, the four-time Silver Slugger and three-time Gold Glove winner has had four 30-homer seasons, including three of the past four years. He's made every All-Star team since 2012, and he's finished second or third in the National League MVP voting three times.
While Goldy led Arizona to the playoffs in 2017 for the first time since 2011, the Diamondbacks faded down the stretch last season and finished a disappointing 82-80.
Per Spotrac, Goldschmidt is set to enter the final year of his contract in 2019, and he will earn an affordable $14.5 million.
Although Goldy is the heart and soul of Arizona's lineup, trading him may be the best move for the organization if re-signing him is unlikely. St. Louis would be a logical landing spot, since the Cards are desperate to get back to the playoffs for the first time since 2015.
The Cardinals went 88-74 last season and finished 2.5 games out of a wild-card spot.
St. Louis has a strong lineup anchored by corner infielder Matt Carpenter, outfielder Marcell Ozuna and catcher Yadier Molina.
The Cardinals ranked 11th in Major League Baseball in both runs scored and home runs last season, and they were 17th in batting average.
Goldschmidt would provide a boost in all areas, plus he would play excellent defense at first and allow Carpenter to focus on third base.
If the Cards land Goldschmidt, the tight race atop the NL Central with the Milwaukee Brewers and Chicago Cubs figures to get even more competitive in what looks like a wide-open National League.