"He is a budding John Hayes, there is no doubt about that," enthused Cantillon after watching his side steal a bonus point in the dying seconds at Temple Hill on Saturday.
Fermoy boy Ross, who arrived at Con from UCC this season, was tipping the scales at 25 stones when the club toured Canada this summer. Now he is trimmed down a bit and put himself about a lot as Constitution secured the victory required to give them top billing in the AIB League.
Ross came in for the injured John O'Driscoll and made a huge impact. He scrummaged powerfully and brought off a number of trademark tackles that international Hayes would have been proud of.
All this brought him close, but not close enough, to winning the man of the match award. Instead that honour went to another youngster scrum half Pat McCarthy.
On a day more suited to water sports, McCarthy showed the lead to his colleagues with a top performance.
His distribution skills were excellent, box kicking occasionally brilliant and he was never slow to have a cut at the St Mary's defence. One blindside break was enough to send him skating through for a crucial try.
Cantillon was, not surprisingly, elated with the five point haul Constitution plundered late in the match. "The bonus point was exactly that a bonus. Not too many teams will beat St Mary's and I can't think of any in particular that might take five points from the fixture. From that point of view, I was particularly satisfied.
"It was a tough struggle for long periods but some of the younger guys, such as Ross, McCarthy and Joey Sheahan came through, while the experience and overall contribution of Ultan O'Callaghan, Jerry Murray and Mick O'Driscoll was very important."
McCarthy who even managed a smile when his attempted conversion of the late try from Sheahan came back off an upright, believes Constitution can turn Temple Hill into a fortress. "That was one of our aims at the start of the season. We reckon we have got to win all our home games by as much as possible and pick up whatever we can on the road. It has been a good start and getting the bonus point might be very important at the end of the season."
St Mary's coach Brent Pope was less enthused with the concession of that last try which denied them the minimum of a bonus point. "That was the most disappointing thing at the end of the day although I was also not happy with the amount of errors we made.
"Con are a very clinical side and they were hugely influenced by the presence of Ultan O'Callaghan. We needed to play the game in their territory but they kept on pushing us back. When they got into our defensive zones they had the killer instinct to put the chances away."
The one bright spot was the display of James Norton, a 27th minute substitute for injured captain Gareth Gannon. Norton came on at fullback to allow Mark McHugh to take Gannon's place in the centre and he made a huge impact. It was his break early in the second half that led to St Mary's opening try from David Clare and he also got a try of his own midway through that second spell.
But when the visitors got that first try to give them the lead for the first and only time in the game they lost concentration and allowed McCarthy the space to restore the balance in Constitution's favour.
"That was a bit of a bummer. It was a bit typical of our performance.
"We had struggled to get into the game, took the lead, and then promptly lost it immediately by making a silly handling mistake near our own line," said Pope.
Constitution deserved their win, forward power and total concentration being the two biggest factors in their favour.
They led 13-9 at the break with a try from Mick O'Driscoll, two penalties and a conversion from McCarthy to three Barry Lynn penalties.
Clare and Norton scored tries for the visitors and Lynn converted one but Con responded with three second half tries from McCarthy, O'Callaghan and Sheahan, while the scrumhalf kicked a penalty and conversion.