The second season franchise are also looking for their first win of 2013 after 30 and 56 point losses to Sydney and Port Adelaide respectively.
Shiel, 20, was quoted in Fairfax Media on Monday as saying the Giants could "run (St Kilda) off their legs", and that any winless team "would be hoping to play Melbourne" for a confidence boost.
Sheedy said such comments could fire up opposition teams.
The veteran coach was seen in earnest conversation with the writer of the article on Monday at the Giants new training and administration centre, and later made it clear he wasn't happy with Shiel's comments.
Asked if he was OK with his younger players talking up their prospects he said, "Not really".
"A lot of our players have only been in the game a year.
"We'll rectify it and make sure that they understand where they are in their position in their career."
Despite the two losses so far, Sheedy said the Giants had been competitive in five of the eight quarters.
He cautioned against reading too much into early season results.
"The first two, three or four weeks I don't look at it too seriously from the point of view of fluctuations in scores," Sheedy said.
"Some teams have got players out that are coming back, and some players probably peak in about that third match.
"I'm pretty sure that St Kilda will be coming at us on the weekend so we've got to look at a very, very experienced lineup to make sure we can handle that."
The Giants will start training at their new Sydney Olympic Park base in around four weeks.
"This is the first time I've had a training ground without a cricket wicket on it in 30 years," Sheedy said.
