The British team, which employed de Jongh until he admitted to his doping past in 2012, won a fourth Tour de France this summer in convincing fashion but at the Vuelta a España they were caught on the hop when Alberto Contador and Nairo Quintana ambushed them in the third week. The episode effectively ended Chris Froome's bid to win a second consecutive Grand Tour.
"There are lots of ways of beating Froome and Team Sky," De Jongh told Cyclingnews.
"Surprise is one - like how you saw in the Vuelta. That was good action. It didn't lead to winning the Vuelta for Alberto because we didn't get enough space but Alberto is good in those kind of moves. That's where he's perhaps mentally stronger."
De Jongh has followed Contador from Tinkoff to Trek-Segafredo for 2017, along with Ivan Basso and two riders. The Spaniard, who has not won the Tour de France since 2009, will go all-out to reclaim a crown that has sat firmly atop Froome's head for three out of the last four seasons.
Froome and Sky's mistakes on stage 15 of the Vuelta have been well documented but at the Tour they have been near faultless in recent years.
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"The Vuelta is different to the Tour but at the Tour you can also have surprises," argued De Jongh.
"If something happens that is out of their control, or that they don't expect, I think that's the weakness of Team Sky."
Complacency has been a factor at Team Sky in the past and, after a disappointing 2014 Tour, it was admitted that they needed to reassess several aspects within their set-up.
"If you're as good as Team Sky and so dominant then you can slip into a relaxed mode and we saw that at the Vuelta," said De Jongh. "If you see that then you can try and take advantage of that.
"Tactically there's a weakness there. Chris is of course a super strong rider but if it comes down to it I think they made some errors at the Vuelta."
'Contador wants to prove he can still do it'
After a difficult final season at the Tinkoff squad, Alberto Contador appears settled at his new team. Word within the team is that the 34 year-old is enjoying the relaxed environment and professional structure.
According to De Jongh, the Spaniard is even stronger than in recent years and, were it not for the crashes that littered his latest campaign, he would have been a far more competitive force in 2016.
"On paper we have a really strong team and I'm looking forward to the year ahead," said the Dutchman. "Two years ago we also had a strong team but here, if we can use everyone on paper then we have a really strong line-up."
Part of Contador's battle this season revolved around a lack of support on the road. He was often isolated, and even at the Tour de France questions were raised over whether one of his own climbers was committing to Contador's cause, or instead riding for himself and a new contract.
With Bauke Mollema, Jarlinson Pantano, Peter Stetina, and a more stable environment at Trek-Segafredo, the two-time Tour winner will be hoping to recapture his form of old. When team boss Luca Guercilena first approached Contador mid-way through 2016 one of the Italian's main selling points was a stable home.
"The Tour is the motivation and he wants to prove to himself that he can still win the Tour," said De Jongh.
"He also wants to show the audience he can do it. That's what has helped him continue. He loves training, he loves the bike so if you can still do results and see that you’re still improving then you come to the conclusion that it's not the right time to stop. He's not been lucky and that's been the main cause of doubt but if you look at races like Paris-Nice and Catalunya he was close to winning. He won Pais Vasco and I think that's where he started to doubt whether he should still stop.
"The competition has definitely become stronger but he's moved up as well when he's been in good condition but this year unfortunately he had some crashes. In 2014 I think he would have won that Tour if he'd not crashed out. In 2015 he was tired after the Giro and this year the crashes were so early it was hard to get a real view of how the competition was."