He started the Timbers' first MLS match in 2011 as a left back and that was his primary position for that first year. From the beginning it was clear he wasn't playing well there but John Spencer, Portland's coach at the time, didn't have many options. In 2012 he started playing in midfield a little, and he showed some promise. The lineup changed too much last year for him to get used to playing there, however.
This season, under Porter, Wallace has become an invaluable part of the attack. He tied the game late in Seattle after coming in as a sub, which, combined with his goal that saved a draw at home to Seattle in September 2012 made him something of a hero to Timbers fans. By April 6 against Houston he had earned a spot in the starting lineup and scored the winning goal at Kansas City, a result that gained the attention of the rest of the league. Sunday against Chivas USA, Wallace continued his turnaround. After the Timbers had come close several times (including a shot off the crossbar by Diego Valeri after a fantastic series of passes by the team), Wallace collected a ball down the left side, settled it with his head, and chipped it over goalkeeper Patrick McClain for the first goal 34 minutes in.
Of course, given the draws in the last two games the Timbers were looking for more goals. No matter the opponent there's always the risk of one mistake turning three points for a win into one for a draw. The Timbers did what they've done so well all year, pressuring the ball whenever they didn't have it and using their passing skill to look for openings in the Chivas defense. Finally, with 20 minutes to go, Wallace found Valeri unmarked (and onside, thanks to Chivas' inattention) in the penalty area for an easy goal. As if that wasn't enough, Will Johnson brought the game to a perfect end with a spectacular curving shot from the top of the penalty area with the last shot of the game. After two games in which the Timbers were unfortunate not to win the 3-0 score was completely fitting for the home side as they were dominant throughout.
With the win the Timbers move into second place in the Western Conference by themselves, and continued to show they really are a top team. With the continued improvement of players such as Wallace there will be more big wins to come.