The biggest shock of the Major League Soccer season came from an unexpected source on Thursday because Landon Donovan announced his intention to return to the LA Galaxy for the rest of the 2016 campaign. 

The club confirmed the acquisition of the all-time leading scorer in league history through a video on Twitter which revealed the 34-year-old will wear No. 26 during his comeback attempt: 

Donovan explained why he's returning to the game he left at the end of the 2014 season through a detailed Facebook post.

No one knows what to expect from Donovan's entry back into MLS, but it's already created a buzz around the club and the league as the postseason approaches. Because of his stature in the game, Donovan's presence on the pitch carries meaning with the Galaxy and the league as a whole. 

Bruce Arena's Galaxy are coming off a 3-3 draw against Real Salt Lake on Wednesday night in which they should've earned three points. However, a howler from Brian Rowe in second-half stoppage time robbed them of earning a crucial road win. 

Donovan won't be able to fix the goalkeeping woes the Galaxy have suffered from, but he will bring an extra element to the attack at the perfect time. 

Giovani dos Santos thrived in the tie at Rio Tinto Stadium as he bagged a brace as the top man in the final third, with Robbie Keane and Gyasi Zardes out. 

If fit, Donovan should be able to step in right away and make an impact with Dos Santos warming up in front of goal and the Galaxy in need of another playmaker, with Zardes out until at least November.

Zardes' absence on the wing is massive because of all the work he puts in, but now that Donovan is back in the squad, the Galaxy have a reliable chance creator with high technical ability to partner with Dos Santos and Keane. 

Donovan and Keane built up a fantastic chemistry in previous seasons, with 2014 being their most successful campaign. During their run to a championship, Keane had 19 goals and 14 assists, while Donovan had 10 goals and 19 assists.

The legends of the international game aren't expected to put up those type of numbers during the final two months of the regular season, but they will make a significant impact on the opponent's game plan.

If Keane, Donovan and Dos Santos are out on the pitch at once, defenses will have to choose who they want to mark out of the game. Keane will stay central at his normal striker position, which means a center-back can keep an eye on him, but containing Donovan and Dos Santos will be a much more difficult task. 

Donovan will most likely play out on the wing in whatever formation Arena decides to use to suit his superstars, while Dos Santos may begin the match centrally or on the opposite wing. Over the course of the match, both players will have the freedom to roam into different areas of the pitch, which should cause plenty of confusion.

The movement of the attackers will be key for the Galaxy, and once they find space they should be able to deliver quality passes to Keane and whoever else finds open space in the box as defenses key in on Donovan and Dos Santos. 

Donovan may not start initially, but if he makes an immediate impact as a substitute and has his legs under him, Arena could throw him into the starting XI at some point during the Galaxy's postseason run. 

But for as dangerous as the Galaxy attack can be with a fully fit Donovan, they still aren't the clear-cut favorites to hoist the MLS Cup on Dec. 10. That title belongs to FC Dallas and Toronto FC for now, but the Galaxy can easily change that opinion in October because they will play FC Dallas on two occasions. 

The Galaxy enter the weekend seven points back of FC Dallas in the Western Conference standings. A win over Orlando City on Sunday is expected, but that may be the only three points they can be sure of capturing in the final stretch of regular-season matches. 

Next Sunday's trip to Sporting Kansas City will be a tough one since Peter Vermes' side is in the hunt for one of the final three playoff berths in the West. Although the Galaxy play Seattle at home on Sept. 25, there is no guarantee they will beat the red-hot Sounders in one of the marquee games of the season. 

LA's playoff position will be determined by their performance in the matches on Oct. 1 and 23 vs. FC Dallas. Anything more than three points from those matches, and a win away at Houston on Oct. 16, should secure at least the No. 3 seed in the West. 

Once the Galaxy get into the postseason, it'll be time for Arena to work his magic. No matter the year, the legendary manager always finds a way to get the best out of his team at the perfect time. The Galaxy will carry extra motivation into the playoffs after falling in the knockout round to Seattle a year ago. The early exit last season marked just the second time in seven years under Arena in which LA didn't advance to the Western Conference Final. 

Donovan's impact will be felt in some capacity on the pitch for the Galaxy, whether he plays 30 or 60 minutes. His leadership and postseason experience will also help in a locker room hungry to get back the MLS Cup.

We're still not sure what exactly the 34-year-old will do on the field, but we already know he's helped the league make a ton of noise with the postseason right around the corner. 

Whether it's a pure coincidence or planned timing, Donovan's return was announced a few days before the Galaxy's latest nationally televised game against Orlando City. The match at 7 p.m. ET on Sunday won't see a massive uptick in ratings due to the return of the NFL, but some viewers who didn't plan on checking out the game may turn over to Fox Sports 1 if Donovan plays. 

The Galaxy are also on Fox next week against Sporting KC and on ESPN the following week against Seattle. If anything, Donovan's comeback will be all over promotional material for those matches and it could draw more fans to watch the games. 

Donovan is MLS. He is one of the few Americans who stayed home during his entire career to build a legacy domestically. If the Galaxy go deep in the MLS playoffs, the plot surrounding Donovan's return will only grow. 

Obviously the league would be ecstatic if the Galaxy made an appearance in the MLS Cup given the stature of the club's players and the new time slot for the championship match on a Saturday night on Fox. But even if LA fail to reach the final, the Donovan storyline will be played up as much as possible. 

There's also a chance Donovan's return is a complete failure. That is the risk anyone runs when they decide to come out of retirement. Sometimes it works out; just look at how well Michael Phelps performed at the Olympics. But there are plenty of examples of athletes who were unable to recapture past glory. 

Donovan's comeback is a great story at the moment, and if it's handled correctly it could help the Galaxy's postseason run and generate momentum nationally for the MLS playoffs. But there's always a risk involved in situations like this. For one of the best American soccer players to ever step on a pitch, it's a risk worth taking in order to capture yet another championship.

Joe Tansey covers MLS for Bleacher Report. You can follow him on Twitter, @JTansey90.