Vick joined the team in time for week 3 of the preseason (the Steelers 4th preseason game, due to Pittsburgh playing in an additional game, the Hall of Fame game.) Due to the timing and circumstances of his signing last year, Vick joined the team days following the end of training camp, and with a couple of preseason games to workout with the team.
The lack of camp time would come back to haunt the Steelers, when Ben Roethlisberger was injured in the Steelers third regular season game. Vick entered the game, and struggled to move the first team offense. He would be further exposed in a terrible situation, where Vick had a short week of practically no practice, to prepare to play the Baltimore Ravens 4 days later on Thursday Night Football. Despite the lack of prepration, Vick may have lead the Steelers to a win, if not for two missed field goals. (Rather, Pittsburgh lost a heartbreaker in overtime, which included two sandlot plays drawn up on the sidelines, since the team couldn't trust attempting a game-winning field goal on two fourth down attempts.)
Vick, would vindicate the loss in the next game against the Chargers, completing a long pass to Markus Wheaton and driving to team to a last-second goal line touchdown by Le'Veon Bell. Following that game, Vick would again struggle against the Arizona Cardinals, before leaving that game with an injury, and making way for the Steelers 4th QB option of the 2015 season, Landry Jones.
Vick would not see the field again in 2015.
While Vick didn't appear effective at times during his tenure, we had suggested on a recent podcast that the quarterback's issues stemmed from a lack of time to learn the playbook. Essentially Vick was tossed into the fire with about 6 weeks to learn the Steelers offense, before going under center. Additionally, he only attempted 10 total passes in his two preseason appearances; hardly time to prep to be a full-time replacement for Big Ben.
When compared with similar scenarios, such as Dallas with Matt Cassell, I'd feel fortunate that Vick was resigned to being a game manager and not attempting to do anything too crazy. We estimate that Vick had maybe 25% of the playbook at his disposal when playing against the Rams and Ravens, and not much more than that a week later against the Cardinals.
Those limitations could've been problematic with Vick having trouble connecting with receivers Antonio Brown and Martavis Bryant as well, something Landry Jones had a bit more success in doing:
Vick to AB: 9 for 19 – 85 yards, 0 TD, 4 first downs
Landry Jones to AB: 12 for 17 – 232 yards, 0 TD, 8 1st downs
Vick to Bryant: 2/3 8 yds, 0 TD, 0 1st downs
Landry Jones to Bryant: 8/16 179 yds 3 TD, 7 1st downs
Landry Jones, who was (and for some still is) not considered a real alternative under center, had a bit more success with those receivers, as well as winning the Cardinals game in relief of Vick (and holding off the Raiders in place of Big Ben.) That should be expected of a quarterback who has been in the Steelers system for multiple years, and it was evident when Landry started calling audibles and protection changes, that he was more capable of handling the offense than the ill-prepared Vick.
Again, this is not entirely Vick's fault, due to lack of time to learn Todd Haley's playbook: something that was a giant criticism of Roethlisberger's chemistry with Haley, during the offensive coordinator's first year in Pittsburgh. That's why I feel a year later, having been exposed to the Steelers system, Vick could be the best option to replace Gradkowski and provide veteran leadership and depth at the quarterback position.
I'm not endorsing bringing him back just trying to clear some things up about his time here..