The Premier League's leading scorer feels that the trio have added to competition for places and is expecting a tough game when Chelsea visit Old Trafford on Sunday
The Premier League champions have started the season with four wins from four, averaging four and a half goals a game, and the former Everton forward feels that the squad's strength in depth has been bolstered by the summer additions.
"Nowadays, when we look at the squad, we see there is a lot of competition for every position and several players with huge quality, such as Phil Jones, who is just 19 years old and has been fantastic," he told Portuguese newspaper Record.
"Ashley Young has also been another instant hit. And then there is also the goalkeeper [De Gea]. We hope the three will be great players."
United face Chelsea, their closest title rivals from last season, at Old Trafford on Sunday and Rooney is expecting a physically demanding game against Andre Villas-Boas' men.
He said: "They have a new coach and it is still unknown whether their playing style has changed. What will not change is their physical strength. We know they always put together a very physical game."
Rooney is currently the division's leading scorer with eight goals in four games and although he is pleased with his performances, the 25-year-old is more keen to focus on the success that the Red Devils have had as a whole so far. However, he is wary of city rivals Manchester City, who are the only other team in the league with a 100% record thus far.
"Yes, this has been a good start. It is great to win games, since we know it is important to start the season with victories and we have been able to do that," said Rooney. "The team have been playing very well and I am very happy to have scored in every game. I hope I will continue doing so."
"There are many teams who fight to win the championship. In previous years, this fight was restricted to four or five teams, but that has changed with City's new strength. They have invested many resources to have a quality team."
The England international returned to top form towards the end of last season as Ferguson's side secured their 19th league title to overtake deadly rivals Liverpool as the top division's most successful ever side, and the significance of doing so was not lost on Rooney.
He said:"It was great to win the championship again, after Chelsea had won it the year before, but winning our 19th championship and breaking Liverpool's record was very good for the players and the fans. It was a big accomplishment."
However, the champions ended the season on a sour note as they went down 3-1 to Barcelona in the Champions League final at Wembley, making it two defeats to the Catalans at the showpiece game in only three years, and the attacker is keen to rectify that in this year's tournament.
"The thing is that the Champions League is the biggest football competition in the world," he said. "Having lost two finals in such a short period of time, we want to improve and be in Munich in May."