It led to his downfall on Tuesday.
The Major League Soccer club fired Rennie after a second straight up-and-down season that saw the Whitecaps start strong before limping across the finish line.
Vancouver recovered in time to squeak into the 2012 playoffs — a first for a Canadian MLS team — but a 1-7-2 slide midway through the 2013 campaign was too much to overcome and cost Rennie his job.
"Ultimately, the rationale behind the decision is the inconsistency," Whitecaps president Bob Lenarduzzi said at a B.C. Place Stadium press conference announcing the move. "If we look back over the two years, we had two relatively good starts, and in each of those seasons we seemed to tail off.
"In the first year we were able to survive that and make the playoffs, but in the second year we weren't able to do so."
Lenarduzzi said the Whitecaps have a "football committee" that includes himself, two of the team's owners and two other executives, which determines the fate of the team's coach, among other duties.
He danced around the question when asked if the decision to axe Rennie was unanimous, saying only that they had come to "a consensus" that it was the right move.
Rennie, who compiled a 24-25-19 record in two seasons with Vancouver, watched the Whitecaps' 2013 playoff hopes come to end when they dropped a 3-2 decision to the Colorado Rapids in Commerce City, Colo on Oct. 19.
Vancouver (13-12-9) rebounded to beat Colorado 3-0 in Sunday's regular-season finale, with star Brazilian forward Camilo Sanvezzo burying a hat trick to win the MLS Golden Boot as the league's top scorer.
But it wasn't enough to save Rennie, who thanked the club and its fans in a statement released on the Whitecaps' official website.
"In life we have different roles at different times, and although there is great satisfaction in taking a project to fruition there is also a strong sense of accomplishment from turning a team around and giving it a solid foundation for future success," the statement read. "It has been an absolute privilege to have played the role that I have for the Whitecaps and I look forward to watching the organization move forward from strength to strength. "
Lenarduzzi said the search for a new coach will begin immediately, and whoever gets the job will be the Whitecaps' fourth in four MLS seasons.
The 38-year-old Rennie's fate was probably sealed when Vancouver stumbled midway through the season, but the Scot also failed to win the Canadian championship in his two years at the Whitecaps' helm, which would have qualified the club for the CONCACAF Champions League.
"There's a fine line between success and, what would be deemed to be failure, and we just need to give ourselves the best chance possible to be on the right side of that," said Lenarduzzi. "Over the last two years we felt that that's perhaps the biggest problem we've had.
"Making the playoffs, winning the (Canadian championship) are benchmarks for us. We haven't been able to achieve that."
There were also questions about Rennie's squad selection, tactics and the development of some of Vancouver's younger players.
"There's always going to be grumblings of guys that aren't happy based on whether they play or whether they think that the manager's way of coaching are valid," said team captain Jay DeMerit, who does not yet have a contract for 2014. "No manager is going to keep 30 guys happy."
The Whitecaps did win this year's Cascadia Cup — their only title since joining MLS — which is a trophy awarded to the top team in head-to-head competition with the Seattle Sounders and Portland Timbers.
Vancouver actually finished with more wins and points this season than it did in 2012 and had just one fewer victory than Portland, which finished as the No. 1 playoff seed in the ultra-tight Western Conference. Vancouver, which wound up seventh, also tied for fourth in MLS with 53 goals scored.
Rennie joined the Whitecaps on Nov. 1, 2011, from the Carolina RailHawks of the second-tier United Soccer Leagues First Division after a disastrous first season in MLS that saw Vancouver go through two coaches and finish tied for last overall.
Prior to Sunday's victory over Colorado, Rennie seemed to be lobbying to keep his job.
"If playoffs was the only barometer, then nine coaches would be gone every single year and that would leave MLS and every team in complete disarray," Rennie told reporters last week. "You can't do it that way. You have to build an organization over time.
"When I came here this team was the worst team in MLS, it was in disarray and it was almost irrelevant in Vancouver. Now it's a very relevant team and it's poised to be a great team, so I'm very pleased with how that's gone."
Vancouver's run to the 2012 MLS playoffs was brief, with the Whitecaps exiting in the first round at the hands of the eventual-champion Los Angeles Galaxy.
DeMerit said although Rennie, who was trumpeted as a young and innovative mind when he arrived in Vancouver, succeeded in helping to build the club's foundation, a veteran coach might be what's needed to take the Whitecaps to the next level.
"At key times, experience does matter, and how you progress is mainly calling on those experiences," said DeMerit. "I think maybe in key moments, that was part of Martin's learning experience and he'll be a better coach for that.
"You want a coach that's been there. You want a coach with experience and you want a coach that can lead you in the right direction when it really matters."
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