Top class tactic here, played two seasons with this to test it out.
First time it was Newcastle United, no transfers in, played this tactic all season. Went into the last game of the season level with Man City, but behind on goal difference. Man City lost their last game, but Newcastle lost 1-0 at Liverpool so finished 2nd. We were champions with 10 minutes to go, but Liverpool scored in the 81st minute.
Second time Birmingham City in the Championship, preseason prediction was 18th but finished 2nd. Leeds United ran away with the division, but Birmingham were safely in the automatic promotion places from about Christmas onward, fell away a bit at the end (4 defeats out of 9 games) but still 10 points ahead of 3rd.
This is a very good tactic, works great getting a steady underdog team seriously over-performing.