Rieder, who made a terrific first impression upon his arrival in Calgary, finishing second to captain Mark Giordano in the team's fitness testing, had four points (2G, 2A) and 11 shots in five pre-season games.
Only Johnny Gaudreau had more.
But it was his play away from the puck that got the attention of the brass over all else.
"I've been killing penalties my whole career," Rieder said. "(The system) changes a little bit when you go from team to team, but I think you've got to have good instincts, you've got to know what they're trying to do."
Last year, Rieder finished fifth among Oilers forwards (and ninth overall) with more than 87 minutes of ice time on the 4 v. 5 penalty-kill.
Rieder, though, played in only 67 games while those ahead of him - Ryan Nugent-Hopkins (82), Kyle Brodziak (70), Zack Kassian (79) and Leon Draisaitl (82) - played more.
Regardless, in that time, Rieder was on the ice for only 12 goals against, while contributing to four short-handed markers - more than any other player.
In addition, his 86.36 on-ice save percentage on the PK led all skaters who regularly appeared in a penalty-killing role.
"Honestly, it's fun," Rieder said. "I love it. It's such a critical part of the game nowadays, so if you can create a role for yourself and do well with it in the process, that's good for me and the team."
Rieder, played more on the PK than any other Flames player in the pre-season this year, says those numbers are the result of a lot of hard work, both on the ice and in the video room.
"There are certain players in the league where you know if he's a shooter or a pass-first kind of guy," he said. "That's where the coaching comes in. If you've done your homework and can see the play developing in front of you, it makes it a little easier to anticipate the play.
"Then, it all comes down to your instincts.
"That extra half second of reaction time can make all the difference between a goal against and a 200-foot clear."