After all, Diggs had started every game he was available since the start of the 2018 season for Matt Patricia's Lions and had signed an extension just one year ago. And yet, Detroit sent the defensive back (and a seventh-round pick) packing for a fifth-round selection.
It was a cruel realization for many in Detroit's building that nothing is guaranteed in this business.
On Tuesday, Slay took to Twitter immediately following the trade, calling Diggs' departure "bull----" and adding, "This one hit me bra." The cornerback elaborated Thursday on his feelings about the move.
"We've been playing together five years," Slay said. "Shoot, team captain, so I mean, for that to happen it's kind of crazy but I guess that's the business part of it. That was crazy, though."
Slay has had a front-row seat to the business part of football in Detroit this year. The All-Pro corner stayed away from the team during a contract dispute ahead of training camp this offseason. Slay has two years remaining on an extension signed in 2016.
Asked if Diggs' trade gave him pause about his status in Detroit, Slay told reporters, "Anybody can get traded but I personally wouldn't care, my personal feeling. Like I said, it's a business. I wouldn't care. It is what it is, go on about the next day."
Slay would be a popular trade piece if he was on the block, but he's arguably Detroit's most important defensive player and the 2-3-1 Lions would almost assuredly be admitting defeat this season if they traded their top corner away.
For now, Detroit must move on and get ready for its Week 8 matchup with the New York Giants. In a tight NFC North, the Lions can't afford to drop many more games, especially those against inferior opponents like New York. For that, they'll need buy-in from players like Slay still reeling from the trade of their former teammate.
Slay said he and the rest of Detroit's defensive backfield are up to the challenge.
"It got nothing to do with on the field," Slay said. "I'm a dog. I just go play ball. That's not going to affect nothing on the field. It will just affect the relationship in the locker room, the (communication).
"I probably got to communicate a lot different with folks because me and Quandre have stuff going on, just like I had with (Glover Quin), how he understood me or how I play, he knew how to play his game from me. Now I just got to build a relationship with other young guys, figure out how we're going to connect all these pieces together."