Here's what I can find on Conacher's year as a defenseman (1940-41) from the NYT:
New York Times 10/29/40 said:
Big Charlie Conacher scored two late first-period goals tonight to lead the New York Americans to a 3-2 triumph over the Rangers...
The defenseman broke away from a Ranger power play, took Anderson's pass and beat Goalie Dave Kerr from close in on the left wing. His second counter came from a right wing spot.
New York Times 11/14/40 said:
Egan, Field and Conacher play the defense positions, while Smith is used as a utility player.
New York Times 11/24/40 said:
Smith and Conacher carried the puck close in for Americans, only to have Goalie Gardiner smother the shot.
New York Times 11/25/40 said:
Jimmy O'Flaherty and Charlie Conacher drove the disk past Bert Gardiner into the Canadien cage...
The Canadiens sought to keep the play in New York ice after yielding this score, but Anderson intercepted a pass and gave the disk to Conacher on the Canadiens' blue line. Conacher moved about two yards into Montreal ice and released a blistering shot that flew past Gardiner for a goal in (sic) 8:56.
New York Times 11/29/40 said:
Through the first period the Americans swept into Ranger territory and had several chances to score. Jackson, Armstrong and Charley Conacher all had shots at Kerr, but the Ranger goalie stood up well.
...
The Rangers had a free shot in the second period when Conacher was detected holding the puck in the American crease. Alfie Pike took the free shot, but fired straight at Robertson.
New York Times 12/1/40 said:
It was Goldup who again electrified the crowd when he flew down the right boards, sped past Egan and Conacher and went over in front to beat Robertson...
New York Times 12/2/40 said:
Buzz Boll, Charley Conacher and Lorne Carr came through with the local markers.
...
Shortly afterward, at 13:24, Charley Conacher took a rebound and caged the puck.
New York Times 12/13/40 said:
Charley Conacher worked furiously on the American defense and came to Robertson's assistance several times.
New York Times 12/18/40 said:
... but when Charley Conacher drove a long shot home for the Americans early in the second frame, the Wings unleashed a heavy offensive...
...
The Wings had a penalty shot following a misplay by Conacher. The drive was made by Arch Wilder, who missed by five feet.
New York Times 12/26/40 said:
When Bauer came on for his second turn in the period, he started from his zone, raced the length of the ice and split Conacher and Slobodian to beat Robertson neatly.
...
Cowley was felled as he split Conacher and Slobodian, but before he lost his footing he rapped a hard shot that Robertson couldn't handle...
New York Times 12/28/40 said:
Then the Bruins kept five skaters in the vicinity of New York's cage, and when Charley Conacher was detected holding the puck inside his team's crease the Bruins earned a free shot. The try was made by Porky Dumart, who drove a high shot past Robertson for the tying goal at 17:25.
New York Times 1/20/41 said:
Fired by this success, the local skaters persisted in their "all out" offensive and tied the count in (sic) 15:33 when Jackson deflected a long shot by Conacher into the cords.
New York Times 1/25/41 said:
Conacher, who got credit for an assist along with Carr, had shot, and Jackson slipped in the rebound.
...
Detroit players bitterly protested a penalty shot Conacher made in (sic) 19:53 to tie it up again. Goalie Mowers had made a nice save of a hard American shot, but as he batted the puck away it stuck to his glove too long and sailed over the screen.
New York Times 1/27/41 said:
Save for Harvey Jackson,... Charley Conacher, Pat Egan, Pete Slobodian and the unfortunate Robertson, the Americans seemed powerless against the hard-charging Bruins.
New York Times 2/4/41 said:
The veteran Charley Conacher, who still has an ear infection, will be available to the Americans if an emergency arises.
New York Times 2/10/41 said:
The third period was half over when Charley Conacher blasted a long right-alley shot into the habitant cords to inform the visitors that it was still a contest.
...
All hands seemed satisfied with the tie as overtime opened, but when Conacher was penalized for tripping Chamberlain [the Habs got caught cheating and the Americans scored shorthanded]
New York Times 2/19/41 said:
Charles Conacher sent one of his long, right-alley shots into the cords in (sic) 1:26.
New York Times 2/26/41 said:
Then [Turk Broda] was caught off guard by Conacher, who fired a sizzling shot past him...
New York Times 3/3/41 said:
At length Conacher took a penalty for interfering with Blake, and this banishment helped the Canadien cause immensely. [Habs scored the game winning PPG with under 5 minutes left]
New York Times 3/7/41 said:
... Charley Conacher came close to tallying when his hard, short drive almost eluded Mowers.
I didn't include references like "X scored with the help of Conacher and Anderson", or "X scored while Conacher was serving a penalty", which are basically just re-stating the box score.
Conacher was listed at a starting defense position in game recaps on 11/14, 11/20, 11/22, 11/25, 12/2, 12/13, 12/18, 12/28, 1/12, 1/13, 1/20, 1/25, 2/24, 3/1, 3/3, 3/9, 3/10, and 3/17. The most common starters on defense were Egan and Field, with Conacher typically skating on the second pair with Slobodian. Notably, when both Egan and Field were badly injured late in the season, the Amerks usually sent Slobodian out to start next to Hooley Smith, with Conacher continuing to come off the bench.
Conclusion: Conacher skated the entire season at defense, with no indication at all of moving to forward. He seems to have been primarily an offensive threat from the blue line. Early in the season he seems to have done more rushing, whereas later in the season there are increasing references to his "blistering" shot. He was not particularly outstanding in his own zone, and had a penchant for ill-timed penalties including at least three penalty shots. Field and Egan were considered the stars of the blueline.
By the end of the season the Americans were a mess of injuries, their defense and goal situation having been mauled so badly that they often skated 3-4 players short compared to their opponent. Conacher was still not given a regular starting spot under these conditions, suggesting that he was viewed as a specialist or at least a counter-punch to take advantage of other teams' depth players. This isn't to say that he played badly, and frankly the team as a whole was so awful that it's kind of hard to separate the individual from the collective struggles..
That argument is not based purely on personal feelings. 
