Not sure who told you that. Unless there's confirmation, I will consider it exactly as likely that he's taking them because he's chosen to lurk on the perimeter for the most part of half-court possessions.
Stevens himself told me that - on multiple occasions:
Stevens on Sully's 3's: "He needs to keep shooting them because he'll make them. All of our guys have to shoot them more freely."
http://www.celticsblog.com/2013/10/20/4860230/celtics-fall-to-love-and-the-timberwolves-89-104The deep shooting abilities of Celtics big men like Kelly Olynyk and Vitor Faverani considered, Stevens is encouraging open threes. He may not have hit against the Knicks, but even Jared Sullinger launched a pair of bombs Wednesday night.
"One thing I heard him say to Kelly and Sullinger on the bench - he yelled at them, actually - don't ever pass up an open three," said Avery Bradley. "He wants us to take open, smart shots. I think we're going to shoot a lot of threes this year, considering that we have a lot of stretch fours on this team."
http://bostonherald.com/sports/celtics_nba/celtics_insider/2013/10/celts_try_to_spread_the_floorAlso, I've got no idea where you're getting the "first half of the season" part. Sullinger has now played in games, and 4 or 5 of them have been stinkers. He strung 2 good games together in the middle of the preseason, but that's about it.
WHAT? There is absolutely no way you've watched these preseason games - and paid close attention - and came to the conclusion that Sullinger has been bad far more than he's been good.
He’s the Celtics’ leading scorer (12.8 ppg) and rebounder (6.5 rpg). He was slightly more subdued last night with 12 points and five rebounds during the team’s first win of the preseason under Stevens, beating the Knicks, 111-81. But for those wondering about the best Celtic during the four games of this preseason, it is quite possibly the same guy who said he wasn’t "close" on the first day of training camp.
http://bostonherald.com/sports/celtics_nba/boston_celtics/2013/10/sullinger_rebounds_on_pure_instinctDuring media day, when Sullinger called himself "not close" to proper basketball shape, I figured he would struggle at least to begin the preseason. Instead, wearing an extra layer of blubber, he's playing like Boston's best healthy player, a great sign for the 21-year old coming off season-ending back surgery.
http://www.masslive.com/celtics/index.ssf/2013/10/boston_celtics_mailbag.htmlGame 1 vs. TOR: 19:58 min, 14 points on 5-11 shooting, 6 reb, 4 ast, 0 TO
Game 2 vs. NYK: 16:06 min, 6 points on 3-7 shooting, 6 reb, 0 ast, 0 TO
Game 3 vs. PHI: 23:14 min, 19 points on 7-15 shooting, 9 reb, 1 ast, 3 TO
Game 4 vs. NYK: 22:26 min, 12 points on 3-5 shooting, 5 reb, 1 ast, 1 TO
Amazing numbers? No. But compare that to Olynyk who supposedly "needs" to start, presumably over Sullinger:
Game 1 vs. TOR: 18:49 min, 4 points on 1-5 shooting, 2 reb, 5 ast, 3 TO
Game 2 vs. NYK: 17:23 min, 4 points on 2-5 shooting, 1 reb, 1 ast, 4 TO
Game 3 vs. PHI: 25:26 min, 13 points on 6-16 shooting, 2 reb, 1 ast, 2 TO
Game 4 vs. NYK: 25:01 min, 15 points on 5-6 shooting, 6 reb, 3 ast, 1 TO
And if you bother to look at the rest of the team's numbers, you'll see that Sullinger's are easily among the most impressive across the first few games, becoming notably worse after Game 4. It's just likely his lack of conditioning has finally caught up to him, hence why he's been pretty average to even below-average recently.
Strange that you seem to be the only one noticing a largely lackluster performance from Sullinger thus far. All of these writers, myself, and other CB visitors must have just been imagining things, right?