Stroman is probably the best starting pitcher on the trading block. The Blue Jays All-Star right-hander has a 3.06 ERA and 1.25 WHIP in 20 starts this season. The 28-year-old is 47-44 in his six-year career with a 3.78 ERA and 1.28 WHIP.

Stroman is actually pretty affordable, as he will only be owed a prorated portion of his $7.4 million salary for the rest of the year. He is also under team arbitration control in 2020, meaning he wouldn't just be a rental for the next few months. That also means Toronto will demand a higher return.

We know the A's have at least inquired about Stroman, though we're not sure how serious those talks were. Several other teams have reportedly shown interest as well and it might be tough for Oakland to get into a bidding war, especially since they won't be open to parting with top prospects like Jesús Luzardo, A.J. Puk, or Sean Murphy.

Still, the thought of Stroman and Mike Fiers atop the rotation, with Sean Manaea likely returning in August as well, has to excite A's fans.

Smith is putting together a phenomenal season for the Miami Marlins. The electric left-hander is 5-4 with a 3.47 ERA and 1.06 WHIP in 15 starts, striking out 101 batters in 83 innings. Smith, 27, is 10-11 with a 4.22 ERA over his brief three-year career.

It's not a guarantee that the Marlins will part with their talented southpaw, as he is making only the major league minimum salary and will remain under team control through 2023. If they do, they will undoubtedly demand a significant return.

Smith would immediately vault to the top of Oakland's starting rotation, along with Fiers, where he would be a mainstay for at least the next few years. If the A's were to reach the postseason this year, a rotation of Fiers, Smith, Manaea, and Brett Anderson would prove formidable. And an ESPN analyst already sees this as a perfect fit.

Speaking of electric left-handers, Ray has put up massive strikeout totals the last four seasons in Arizona. The 27-year-old is 9-6 this season with a 3.95 ERA and 1.31 WHIP in 22 starts, notching 162 punchouts in 123 innings. He has averaged 12 strikeouts per nine innings in each of the last three years and has a career ERA of 4.04 in six big-league seasons.

Ray is also affordable financially, earning $6.05 million this season and under arbitration control next year. Of course, this once again means the asking price will be high and multiple teams, including the Yankees, are reportedly interested. The Diamondbacks could also choose to keep Ray, as they are still within three games of a National League wild-card spot, though they would have to pass four teams.

If the A's did acquire Ray, he would be a great option to start a potential wild-card game, depending on the matchup. When the hard-throwing southpaw is at his best, his stuff is overpowering.

The A's could also use some bullpen help and Greene would be a tremendous addition. The Tigers All-Star closer has been terrific this season, maintaining a 1.25 ERA and 0.86 WHIP with 40 strikeouts in 36 innings. The right-hander has converted 22 of 25 save opportunities.

Greene, 30, is earning $4 million this year and is under arbitration control for 2020. He would certainly give A's manager Bob Melvin another quality late-inning option out of the pen, joining Liam Hendriks and Yusmeiro Petit.

Of course, the bullpen is probably not quite as big of a concern as the starting rotation in Oakland, especially with the expected addition of top prospect A.J. Puk sometime next month. Still, teams can never have too many quality relievers in the postseason.

Giles would be another excellent bullpen option for the A's. The Blue Jays right-hander is 1-2 with 14 saves and a 1.64 ERA in 33 appearances this year. He has an almost unbelievable 57 strikeouts in just 33 innings, a rate of 15.5 punchouts per nine frames.

Giles, 28, has a career ERA of 2.69 in six major-league seasons. He is earning $6.3 million this year and is eligible for arbitration in 2020. Giles would look great as a setup man for Hendriks, or even another option to close games for Oakland.