Updated Tuesday afternoon with a clarification of the roster rules fromMLS headquarters.

The Union announced on Monday that they finalized a deal to bring in Portuguese-Canadian central defender Steven Vítoria from Benfica on a one-year loan, with an option to purchase Vitoria's rights afterward.

As I alluded to on Friday after KYW's Kevin Kinkead broke the news of the Union's interest in Vítoria, the 6-foot-5 28-year-old is likely to step straight into the starting lineup as a replacement for Carlos Valdés.

"We're excited to bring Steven in and feel he is an excellent fit for the club," Union technical director Chris Albright said in a statement issued by the team. "He has the ability and experience to make an instant impact for us and is a player we're expecting big things from."

If you are the kind of fan who (for good reason) refuses to believe player signing stories until you see the player with his new team's jersey in hand, the Union had you covered as soon as the deal was announced:

Now it's up to Albright to find the last big piece of the Union's offseason puzzle: a striker who can match wits with Jozy Altidore, David Villa and Juan Agudelo in the race for the playoffs.

One thing I forgot to note in explaining Vítoria's backstory last week is that when he played for Estoril, he helped the club gain promotion to Portugal's top flight. So even though he hasn't played on soccer's biggest stages yet, he nonetheless has some experience in pressure situations.

"I'm ready to come in and contribute any way I can to help this club win games," the Toronto native said in a statement issued by the team.

That's a good thing, because the Union had to do more than just strike a deal with him in order to secure his services. For lack of a better way to put it, they had to pay off the Vancouver Whitecaps to gain the right to negotiate in the first place.

Get out your copy of the MLS Roster Rules, because things are about to get weird.

Vancouver had Vítoria on its Discovery list in 2014, which is a set of players outside MLS that each club in the league can claim the first right to neogtiate with if said players want to enter the league.

At some point in 2014, the Whitecaps tried to sign Vítoria, and it got to the point where they made what MLS headquarters considered to be a "bona fide" offer. Vítoria refused it, as he didn't want to play for the team.

But Vancouver kept his MLS rights, simply because of having made that offer. Yes, really. Here's why.

Those of you who are well-versed in the arcane logic (or sometimes lack of logic) in MLS' roster rules may have raised a red flag at the phrase "bona fide." That's the same phrase used when a player leaves a MLS team to go to Europe, and that team makes a contract offer which allows it to keep the player's MLS rights in perpetuity.

You may also be aware that discovery claims - which have been part of the league's roster rules for many years - expire at the end of each season. Lo and behold, the right of first refusal that results from making a bona fide offer to a discovery claim player does not expire.

Because of this, the Union had to send allocation money (an undisclosed amount, as ever) to Vancouver in order to gain the ability to sign Vítoria. MLS is notoriously secretive about the sums of allocation money that move in trades. I do know, however, that the minimum requirement for allocation money in a trade which includes it is $50,000.

Here is the section of the Roster Rules that explains (as such) how Discovery claims work:

(E) DISCOVERY SIGNINGS

Clubs may make discovery claims on players not yet under MLS contract who are not subject to the allocation ranking or lottery mechanisms. 

Each club has the opportunity to make six discovery signings per season (expansion teams may make 10 discovery signings in their inaugural season). A club may have up to 10 discovery claims on unsigned players at any time and may remove or add players at any time. The last day for discovery player signings is September 15, 2014 - coinciding with the roster freeze date and trade deadline. 

The six discovery signings can be used to fill senior roster spots only. If multiple clubs claim the same player using a discovery, the club that filed the claim first will have first rights to the player. Discovery claims expire following each season. If the League and player are unable to reach an agreement during the season, the club that first filed the discovery retains the right of first refusal in the event the player is later signed by the League.

[...]

Note: To protect interests of MLS clubs in scouting and negotiations with prospective players, the League office will not publicize the names of players on club discovery lists, nor specify if a discovery claim has been filed on a particular player.

(The real meaning of that "note," as you might have already figured out, is that keeping discovery lists out of the public domain decreases the odds that clubs will bid against each other for a player, and thus helps keep salaries down across MLS.)

You might look at all the legalese above and conclude that the phrase "Discovery claims expire following each season" contradicts the phrase "retains the right of first refusal."

Were I the one writing the roster rules, I'd - well, first of all, I'd get rid of Discovery claims, not to mention the allocation process and weighted lotteries for Americans coming into the league from abroad.

I've beaten that horse plenty over time (and let the record show that with all due respect to the animal rights activists out there, the horse still isn't dead yet).

Anyway, it would make more sense if the clause in question said "If the League and player are unable to reach an agreement during the season after the club holding rights attempts to negotiate with the player and makes a bona fide offer..."

That missing language is indeed how things actually work at MLS headquarters, according to a spokesperson for MLS who I chatted with on Tuesday.

In order for a team to claim the right of first refusal, there must be a legitimate negotiation between both sides - preferably an offer and a counter-offer. A club can't just put Cristiano Ronaldo on its Discovery list, then claim to make a contract offer that gets swatted away immediately by Ronaldo and Real Madrid.

Here's the kicker: the judgement on what constitutes "legitimate" comes down to the league office. The decision-makers in New York must decide not only that a team has a legitimate chance to sign a player, but the terms offered must also satisfy the league office's own value of the player.

That language, I'm pretty sure, will set off alarm bells for some readers - especially those in Vítoria's home town.

In this case, there was a legitimate negotiation between Vítoria and the Whitecaps that didn't result in a deal, so the Whitecaps got the right of first refusal.

If, say, Vancouver put Ronaldo on its discovery list and thrown a contract at him for the hell of it that he dismissed out of hand, MLS would not have counted that as a "bona fide" contract offer. So the discovery claim would have expired at the end of the 2014 season.

(Officially, discovery claims reset the day after the MLS Cup final.)

Union fans can only hope that the amount of allocation money surrendered wasn't all that big. Because it's not going to be made public unless someone lets slip information that they aren't supposed to.

Last month, MLS commissioner Don Garber noted (not for the first time) that "transparency is more and more important" for his league on the eve of its 20th season. Disclosing sums of allocation money in transactions - never mind abolishing many of those byzantine roster rules - would help the cause.

So too would an insistence by the MLS Players Union on enforcing transparency in the new collective bargaining agreement.

Thus far, neither side has shown much of an interest in such changes. Meanwhile, soccer fans on the Atlantic and Pacific coasts are left wondering when the Whitecaps will be stung traversing the bramble that the Union have navigated over the last few days.