Well, now I see why I missed your comment the first time...it wasn't even on my talkpage; I read it on someone else's talkpage (Broxton's) and got confused, haha.  But anyway, yeah.  To give a good example of a "cup of coffee" MLS transaction, let me go back to Toronto's actions in the expansion draft of 2006.  In expansion drafts, clubs have the option to "protect" a certain number of players while leaving others "unprotected".  Unprotected players can be drafted at will by the expansion franchise (Toronto in this example), who can take one from each team.  One of the league's clubs, Real Salt Lake, made a strategic gamble that they could leave one of their key/totemic players, Jason Kreis (now their manager), unprotected.  They assumed that TFC would want nothing to do with an aging player whose oversized salary would be a big hit on their cap.  Seeing an opportunity, Mo Johnston at TFC took Kreis from RSL in the draft...not because he actually wanted Kreis, but because he knew that RSL still needed him.  By doing this, TFC was able to briefly hold Kreis hostage until RSL agreed to trade something else of value to get Kreis back.  So, Kreis was briefly a TFC player, but only because he became a pawn in larger machinations.  Because of instances like this, which are common enough throughout league history, we seem to have a consensus to disregard in-and-out situations during the offseason.
And for a bit of further detail — not relevant to Atieno and USL players but important as a point of reference for many other US-based players — it should be noted that MLS has a single-entity corporate structure, and that technically all players are contracted by the league itself, not by individual teams.  This means that all listings of player tenures with MLS teams are de facto in the first place, and that gives us a bit of leeway in striking out certain unimportant and very temporary tenures, as in the example given.  Hope that helps. ''' 《Defender of Open Editing》'''