McKenna, a veteran of 14 pro seasons has been on five teams in three NHL organizations this season. He has played at least one game at four of his five stops.
He started the season in Belleville (American Hockey League), was called up to the Ottawa Senators and then was traded to the Vancouver Canucks on Jan. 2. Two days later, he was claimed by the Flyers after Vancouver had sent him to Utica (AHL). He is one of seven goalies to play for the Flyers this season.
With the 2019 NHL Trade Deadline on Monday at 3 p.m. ET., the idea of trading a goalie and the challenges inherent in such a transaction are noteworthy.
[RELATED: Full NHL Trade Deadline coverage]
There hasn't been much talk about goaltenders moving this season because most teams in contention for the Stanley Cup Playoffs are comfortable with their tandems. Sergei Bobrovsky of the Columbus Blue Jackets, Jimmy Howard of the Detroit Red Wings and James Reimer of the Florida Panthers reportedly have drawn the most interest.
The biggest challenge for a traded goalie, says McKenna, is having enough time to make the necessary adjustments before the start of the playoffs, which will begin April 10.
"I think after 10 or 15 games played, both a goalie and their defense should be able to adapt and find common ground," said McKenna, who reached the AHL's Calder Cup Final in each of the past two seasons.
Teams usually have about 20 games remaining in the regular season after the deadline. It's unlikely the incoming goalie plays every game because of back-to-back situations and a need for rest. Precious few extra games remain if the transition doesn't go smoothly.
Patience through that adjustment process isn't easy, especially if a coach isn't secure in his team's positioning for the postseason.
"By the time a goalie adapts it can be too late," McKenna said.
McKenna, loaned to Lehigh Valley (American Hockey League) by the Flyers after clearing waivers Thursday, has played for 24 teams in the ECHL, AHL and NHL since turning pro in 2005 after being selected by the Nashville Predators in the sixth round (No. 172) of the 2002 NHL Draft.
Video: PHI@WSH: McKenna gets across to rob Ovechkin
Understanding the transition elements involved in the move from one team to another can help identify goalies best suited for the transition.
One of the big questions is whether the goaltender has done it before.
"It's a really tough transition, especially if it's someone who has been in one organization for years and had a team built around them," McKenna said.
Other factors include whether a goalie's style and strengths match the defensive system and the resulting scoring chances his new team allows. It can include everything from the number of rush chances compared to end-zone shots, to how net-front traffic is countered. The number of shots matters as well. Some goalies are more comfortable seeing a lot of shots but struggle when they aren't busy.
When Ryan Miller was traded from the Buffalo Sabres to the St. Louis Blues on Feb. 28, 2014, it raised some of those caution flags.
It was Miler's first trade after 11 seasons with the Sabres. His new team, the Blues, gave up fewer shots and rush chances. Miller, who played with more backward flow in his game, was not as suited to a low-shot atmosphere. The defensive-zone reads around the crease also changed for a goalie who, at the time, relied more on anticipation.
Video: ANA@MIN: Miller absorbs Zucker's heavy one-timer
Miller, now with the Anaheim Ducks, went from a .923 save percentage in 40 games with a struggling Sabres team to a .903 save percentage in 19 regular-season games and dropped to .897 during a first-round playoff loss with the Blues.
That trade has become a cautionary tale for teams looking for a goalie to put them over the top.
Looking back at the trade a couple of years later, even Miller admitted it wasn't an ideal situation.
"It's hard to change gears," he said in 2016. "You almost have to go to a different mindset, different system, different expectations, just a lot of new things all at once."
Miller has since said he is better equipped to make a quicker adjustment to a new team, in part because the Ducks are his fourth team, after a three-year stint with the Vancouver Canucks, and in part because his playing style has become less aggressive and more adaptable.
Still, finding the perfect fit between goaltender and system isn't always easy.
Goalies can adapt, but making the right reads and predicting plays properly is not solely a function of anticipating what attacking players will do. Much is predicated on knowing what your team is trying to force the opposition to do, what options teammates are responsible for taking away first and what remains to be done by the goalie.
Understanding those preferences is the first step. Trusting teammates to execute is another. Putting it all together can take time.
For Calvin Pickard, that process took almost two months this season with the Arizona Coyotes, his third NHL organization in 2018-19. Pickard was set to begin the season with the Toronto Maple Leafs, but was claimed off waivers by the Flyers on Oct. 2. He played 11 games for Philadelphia before being waived again and claimed by the Coyotes on Nov. 29. Pickard didn't play for a month because of injury before going to Tucson in the AHL for a conditioning stint in early January.
He made his Coyotes debut on Jan. 23.
"It took me a long time because I never played," Pickard said. "I am just getting to that point now where I am feeling comfortable and earning the trust of teammates and the staff."
Reimer made a quick adjustment after being traded to the San Jose Sharks from the Maple Leafs at the 2016 deadline. Reimer was 6-2-0 with three shutouts and a .938 save percentage in eight starts for San Jose, partially because he quickly changed his style, playing deeper in his crease than he did while in Toronto.
"There is usually a bit of a feeling-out period," Reimer said.
Unfortunately, time is usually of the essence when it comes to that process when the trades are made around the deadline.