"Obviously, I know from the fans this will be a tough one," general manager Alex Anthopoulos told the media Tuesday before the game against the Kansas City Royals.
He then left open the door for the return of either player.
"I have not ruled out either player being back here in 2012," Anthopoulos said.
So this might be not be a final goodbye, after all.
All three players in the deal could become free agents in the offseason. Hill, McDonald and Anthopoulos all talked about the possibility of returning to the Blue Jays, depending on how things work out and what the team needs. Neither Hill nor McDonald discouraged talk that a return to Toronto could happen, although it would obviously depend on Toronto's needs.
"This is all I've known, this has been my family," Hill said. "Like Alex said, I'm very open to coming back next year. This isn't the end."
"I've had a lot of conversations with Alex recently about just that, about continuing to be a Toronto Blue Jay and that excites me too," McDonald said.
Johnson is not expected to join the team until Wednesday, but might not arrive in time to start the game.
While McDonald's role with the Blue Jays was as a backup infielder, who excels defensively and has become a better hitter over the years, Hill is a regular second baseman.
And the Blue Jays want to take a look at the 29-year-old Johnson, who has appeared in 114 games for Arizona this season, posting a .209 average to go along with 18 home runs, 49 RBIs and 13 stolen bases. A first-round pick of the Atlanta Braves in 2000, Johnson is a career .260 hitter with 89 home runs and 326 RBIs in 758 games.
"He has the ability to get on base, draw some walks and he's got power to all fields," Anthopoulos said. "He'd be the first one to tell you, I'm sure, he's not performing the way he expected to, especially off the year he came off of last year."
Players must clear waivers to be traded after the July 31 non-waiver Trade Dealine, and Anthopoulos said all the Blue Jays players cleared early in August as a matter of club policy.
It was at that time that talks with the Diamondbacks on a possible deal started to take place.
Hill has struggled the last two seasons with the Blue Jays, but said he will cherish his time in Toronto, noting the club's bright future.
"This year's been a little rough," he said. "It hasn't been the year I wanted it to be. But at the same time you go out there, you prepare ... and you keep going."
But he feels the work he has put in with Blue Jays hitting coach Dwayne Murphy was making a difference in the past week, and he hopes it carries through with Arizona.
"They've been role models for the young players and everybody else in the city," Anthopoulos said of Hill and McDonald, who were two of the longest-tenured players in the Toronto franchise. "All that said, both with potential to be free agents at the end of the year, there's certainly uncertainty with respect to 2012. This is a chance to put them on a team in first place with the chance to go to the postseason."
"They were guys that cared," manager John Farrell said. "They were guys that came ready to play and compete whether they were known to be in the starting lineup or whether they were there to be ready to be on call. True professionals. Just very good teammates, very good players."
The D-backs, the surprise front-runners in the National League West, have had a bit of a hole in the infield since everyday shortstop Stephen Drew was lost for the season with a fractured right ankle. With this deal, they acquire two veteran infielders who can lend a hand.
"My opportunity to play for the Diamondbacks for the next five to six weeks plus the postseason is a great opportunity, an opportunity I wake up every morning thinking about," McDonald said. "It's what every baseball player wants."
Hill, a first-round selection in the 2003 First-Year Player Draft, was hitting .225 with six homers and 45 RBIs at second base for the Jays this year. He had a banner year in 2009 when he drove in 108 runs, scored 103 more and smacked 36 home runs -- all career highs.
McDonald, 36, was batting .250 with two homers and 20 RBIs this year in a utility role for the Blue Jays. He owns a career .240 batting average in 13 seasons with Cleveland, Detroit (where D-backs manager Kirk Gibson was his hitting coach) and Toronto.
Hill and McDonald also will rejoin first baseman Lyle Overbay, who was a Blue Jays teammate in recent years . Overbay started the season with the Pirates and recently caught on with Arizona.
"I have a lot invested here in Toronto, in the organization, in baseball, my family," McDonald said. "There's a lot of feeling that you belong in the community and you've been able to become part of the community. You feel sometimes you mean a lot more to Toronto than just a baseball player, which is a pretty neat feeling.
"It's also just a great feeling knowing that I have an opportunity to come back here as soon as next year," he said. "There's a lot of good feelings. I'm excited about what could happen to me, I'm excited about what it could do for my career going forward. The only negative is walking out the door and not being a Blue Jay for the next six weeks."
"This team will win," Hill said. "The way they're going, the direction they're going, with Alex and everybody, I do believe this team will win. Whether I'm a part of that or not I'll be rooting for them because this is a special place. Not only are you playing for the city of Toronto but the country of Canada. It's a very special place and it will be missed."
Larry Millson is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.