MLS teams don't spend much on outside backs. They've been only marginally affected by increases in the salary cap, none are Designated Players permitted per team, and no team has yet spent any Targeted Allocation Money to sign one.

The three-man back line is gaining favor in MLS as well as around the world, but the standard four-back system prevails. Occasionally, a player will toggle between the central slots, but most players and coaches prefer to establish one side as their own. Steve Birnbaum has played well enough to earn callups to the U.S. national team, and in his first MLS season Jelle Van Damme has displayed the toughness and savvy acquired during more than a decade of play in Europe.

Not many MLS teams field a truly dominant winger or wide midfielder; two that did, Seattle and Montreal, reaped the benefits. Nicolas Lodeiro led the Sounders to their first league title and Ignacio Piatti propelled the Impact to its first appearance in the Eastern Conference finals.

For players who toil in the middle of the park, roles and classifications often overlap as tactics and formations change from game to game or even within a game. Coaches and general managers and pundits talk of a "No. 10," the playmaking hub around which the attack revolves, yet in many leagues around the world - including MLS - what was traditionally a passing position has broadened to include players who can score goals as well as consistently set them up.

Two players hit the magical 20-goal mark in the 21st season of MLS. Bradley Wright-Phillips scored 24 to notch his second Golden Boot and he tops our list of the league's best strikers, just ahead of 23-goal man David Villa. Sebastian Giovinco, the 2015 MLS MVP, ranked as top forward after another outstanding season.

MLS announced details of the timetable for the next wave of expansion that will take the league from 24 to 28 teams. MLS commissioner Don Garber mentioned 10 markets that have expressed interest in bidding. Here's a look at how these markets stack up, who's behind their bids and what stands out about soccer in them.

Seattle and Toronto personify the ambition shown by many big-market MLS teams, and after long years of frustration in both cities those teams have reached their first MLS Cup final. It is fitting that they meet in the 21st edition of the league's showcase event.

Jordan Morris has gotten a lot of good advice in his rookie year from teammates and coaches on the Seattle Sounders, from national team players like Michael Bradley and Jozy Altidore whom he'll face when the Sounders play Toronto FC in MLS Cup 2016 and from his family with which he still lives. But perhaps the simplest advice came from Nicolas Lodeiro when the Uruguayan joined the Sounders in late July.