The MLS roster freeze - the date on which 28-man squad lists for the rest of season must be submitted to the league - was September 15, so naturally the New York Red Bulls announced a new signing on September 16.
The new man is a familiar face: NYRB II's Aaron Long. The versatile defender (he can play, more or less, all four positions on the back line and as a holding midfielder) has already made two starts for the first team in CONCACAF Champions League, so he is no stranger to the MLS squad. He has emerged this season as the II-team's most consistent and polished defender, usually playing at center back.
RBNY is the third MLS team to have a look at Long: he was drafted by Portland Timbers in 2014 (the same draft that brought Chris Duvall to RBNY); the 23-year-old (24 in October) signed with Seattle Sounders in the middle of his rookie season; the Red Bulls gave him a contract with their USL team for 2016.
He has yet to make an appearance in MLS, but has been a regular in USL for the past two seasons (2015 with Seattle Sounders 2; 2016 with NYRB II). His role in the II team's exceptional year has long recommended him as cover for the senior squad, and that would appear to be the principal motivation behind his promotion to the first team.
The official announcement states Long is on loan from NYRB II, and will remain available to play for both the MLS and USL sides of the club's pro set-up. As such, it is effectively the inverse of the usual MLS-to-USL loan that sees players like Derrick Etienne, Brandon Allen, Justin Bilyeu and Tyler Adams regularly turn out for the reserves.
The deal raises a few questions about the sort of transactions allowed between MLS squads and their USL reserve teams. This is not, for example, the same short-term loan arrangement that allowed Long to play in CCL. But none of those questions will be settled here. And the important thing to note is - by whatever mechanism Ali Curtis found to achieve it - RBNY has secured defensive cover for its end-of-season push for silverware.