Over the last month, Oakland general manager Billy Beane hasn't been the least bit shy to pay a premium price for the Athletics to boast one of the most feared rotations in baseball.
Beane recently has gone away from the "Moneyball" tactics that made him famous, dealing his top two prospects to acquire starters Jeff Samardzija and Jason Hammel from the Chicago Cubs on July 4 and trading Cespedes to Boston for Lester and outfielder Jonny Gomes.
Though the A's (66-41) added another strong arm to a rotation that already leads the AL with a 3.32 ERA, Cespedes is signed through next season while Lester could wind up being a short-term rental if he bolts in free agency this offseason.
Beane also sent disgruntled starter Tommy Milone to Minnesota for outfielder Sam Fuld on Thursday.
"Players like this really don't come along too often," Beane said of Lester. "When you get a guy who's a legitimate No. 1 starter in the middle of the season and we currently sit in first place, we're excited. ... There's no looking ahead."
The loss of Cespedes, though, could affect an offense that leads the majors in runs scored. He was third on the club with 17 homers and 67 RBIs.
"Cespedes is a big bat that's going to be missed," shortstop Jed Lowrie told MLB's official website. "(The organization) always hung (its) hat on pitching. I think this is another example of that."
It's difficult to argue that logic with Oakland possessing the majors' best record and a two-game lead over the Los Angeles Angels in the AL West, largely due to its solid staff.
Gray (12-3, 2.65 ERA) has been one of the rotation's stars and was stellar in five July starts, winning each while posting a 1.03 ERA. He gave up one run in 6 2-3 innings of a 5-1 victory over Texas on Sunday and struck out five to give him 31 over 35 innings during his hot stretch.
"The numbers speak for themselves," manager Bob Melvin said of Gray, who could tie Detroit's Max Scherzer for the AL lead in wins Friday.
The right-hander has never faced the Royals (55-52), who didn't make a move at the trade deadline despite trailing the Tigers by just four games for the AL Central lead.
As Detroit bolstered its rotation by acquiring David Price from Tampa Bay, Royals general manager Dayton Moore is prepared to move forward with the current roster.
"You can only take advantage of what's available to you," Moore said. "We feel this group of players is very talented and able to produce."
The failure to add depth could be a problem, though, as first baseman Eric Hosmer will be out 3-6 weeks after aggravating a finger injury in Thursday's 6-3 win over the Twins.
"Very frustrating," Hosmer said. "The good thing is I can still get back for that last month and make that last push."
Kansas City looks to avoid a fifth straight loss in Oakland behind Jeremy Guthrie.
Guthrie (6-9, 4.70) saw his three-start losing streak end Sunday, but mostly because of run support. He gave up five runs and 10 hits in 5 2-3 innings of a 7-5 win over Cleveland, putting his ERA at 10.07 over his last four starts.
The right-hander hasn't faced the A's since Aug. 14, 2012, when he allowed three hits in seven innings of a 5-0 win.