ST. LOUIS – They're the newest recruits on a US national team squad built with transition in mind as the 2018 World Cup cycle begins.

But the arrival of Darlington Nagbe is merely the final step in a grooming process that dates back years, head coach Jurgen Klinsmann told reporters on Thursday at Busch Stadium – an ascension capped by their strong displays in MLS this season.

“A player like Darlington or like Matt Miazga or other ones that came in over the past year, they're coming in because of their very, very good performances in their club environment. And because of a lot of conversations with their club coaches,” said Klinsmann in his pregame press conference one day before the USMNT open their qualifying campaign vs. St. Vincent & the Grenadines in front of a packed crowd of 45,000-plus at the celebrated home of baseball's Cardinals (4:00 pm PT, ESPN2/WatchESPN/UniMás/UDN).

But will they play in this month's games?

Klinsmann typically eases newcomers into his program, calling them up for multiple camps before granting significant playing time, and he explained his reasoning for that on Thursday. But many are wondering if that rule of thumb still applies with this duo. Nagbe is already 26 and in red-hot form for the MLS Cup-chasing Portland Timbers.

“We try to figure out when is a good time for their introduction. Obviously Darlington is a special case, because we needed to wait for his [citizenship] eligibility with the US,” said Klinsmann. “I'm talking about him with [Portland coach] Caleb Porter since three years.

“So it's a progression, and it's a progression from their club environment into our environment, and then hopefully find the right time in our environment to give them the start, to give them their first cap, which means a lot, obviously, to the player. We are not making those decisions overnight.”

Nagbe has not spoken to media while with the USMNT this week. But media reports have suggested that the Liberian-born midfielder may have even impressed the US coaching staff enough to earn minutes on Friday night.

“We'll see – I think he'll be in a few more camps still,” predicted DeAndre Yedlin with a grin.