Among a crowded throng of contenders in the National League, the Cardinals are reportedly interested in bolstering their lineup ahead of the July 31 non-waiver Trade Deadline -- and potentially with a bat they were prominently linked to last offseason. 
In a story for The Athletic on Friday, MLB Network insider Ken Rosenthal indicated that St. Louis has "renewed interest" in acquiring Royals third baseman Mike Moustakas, who the club was tied to throughout most of last offseason during free agency. Doing so, however, could create roster complications. Bringing in the left-handed-hitting Moustakas, who would balance a righty-heavy lineup and has a .255/.310/.467 slash line with 15 homers, would likely force Matt Carpenter to first base.
The ripple effect could also mean removing surging Jose Martinez, who is batting .305 with 12 homers this season. Martinez isn't praised for his defense, but the Cardinals would miss his consistent offensive production if Carpenter took over at first base. Another option for the Cards would be to move Carpenter to second, replacing slumping Kolten Wong, who is batting .196 with a .632 OPS. St. Louis ranks third in the NL Central and sits 4 1/2 games back from the first-place Brewers, and it ranks 19th in the MLB in runs and team batting average.
But who would the Cardinals trade for Moustakas? Rosenthal speculated that the team might make multiple deals, aiming to alter the roster it has right now. The Cards could deal Martinez, who is under contract through 2022, to teams looking for a bat. Or they could find someone to take outfielder William Fowler, who still has three-plus years on his $82.5 million contract. Fowler is batting just .167 with five homers this year.
Righty Carlos Martinez, who signed a five-year, $51 million extension in 2017, might also be the focus of inquiries. Martinez has been shaky this year, with a 4-4 record and a 3.22 ERA, and returned from the disabled list in early June after a right lat strain injury.