François Parenteau of "La Presse" wrote a good article on Jérémy Grégoire, and why he 'fell' to the sixth round of the draft in 2013.
He explains that Jérémy was always a first-grade prospect, but he struggled in his draft year playing for the Saguenéens, to the point where he asked for a trade at the Christmas break. This may have set off alarm bells in the scouting community, that this kid might be a little too big for his britches.
The author continues that the trade to Baie-Comeau was ultimately beneficial though. His first LHJMQ season saw him pick up 30 points in 61 games, but he was stuck at 15 points in 35 games the next season when he asked for the trade. He finished with 17 points in 27 games for the Drakkar, and blew up in the playoffs with 16 points in 18 games.
One reason for his lack of success in Chicoutimi may have been a rift with his coach, who no longer is the Sags' head coach and is back in the CIS with the UQTR Patriotes this season.
The comments to the article also provide some insight. One poster explains that the olympic-dimension rink in Chicoutimi didn't suit his physical style. While he has improved his skating this season, the larger ice surface supposedly didn't play to his strengths, and he is much better suited to a North American-sized rink.
Another commenter goes further than the article's author, and states that the coach plainly didn't like him, and didn't rely on him overly. Of course this can make all the difference in the world, in terms of the player's confidence, and the minutes he receives and situations he plays in (powerplay, offensive situations)l.
So Jérémy Grégoire, who was headed for a disastrous draft year, being left off the NHL's Central Scouting mid-season prospect rankings, managed to save his season and ended up ranked as the 79th North American prospect by Central Scouting. He was drafted 176th overall by the Canadiens, and last season was a point-a-game player.