Harrington's contract is a low-risk attempt by Washington to strengthen their lineup by adding some depth on the bench, only tying up a reported $1.4 million for one year with the 33-year-old.
On an otherwise young team, Harrington brings 15 years of NBA experience to Washington, playing for seven different teams since coming into the league out of high school.
But Harrington cannot come onto the Wizards roster and automatically succeed. There are several changes to Harrington's game that he and the coaching staff must work on and decisions that need to be made if this relationship is to work.
Harrington has already predicted that the Wizards can make the playoffs, but they will only be able to do that with Harrington as a main player if he and the coaching staff do these four things.
Limit Harrington's Minutes
It's not a secret that Harrington has constantly struggled staying healthy throughout his career.
Most recently, he only played in 10 games with the Orlando Magic after missing most of the season with a staph infection.
Prior to that, he only played one full season out of 12 and missed the 70-game mark five times.
Washington's other veteran power forward Nenê has also had injury issues, so splitting minutes between the two is likely to increase the amount of games both will play.
There's no clear-cut starter yet at power forward, but the most likely scenario is a split of starts between Nenê and Harrington.
The days of Harrington playing 38 minutes per game are long gone, and a combination of he and Nenê playing roughly a combined 35 minutes would still leave time for younger power forwards such as Jan Vesely and Chris Singleton to get some experience.
Singleton has a lot of untapped talent, and, if Vesely improves his play, he could possibly become a trade piece along with small forward Trevor Ariza.
Harrington is certainly a talent who brings a new dimension to Washington's offense when he's on the floor, but the Wizards want to make this signing worth their time they'll take every step necessary to keep him healthy.
Allow Harrington to Stretch the Floor
One of Harrington's best assets is his outside shooting, which took many years in the league to develop.
Although Harrington averages about 35 percent shooting from three for his career, he shot 43.75 percent from behind the line during the 2006-07 season and 36.75 percent during the 2008-09 season.
During the 2011-12 season when he played with the Denver Nuggets, Harrington shot 33 percent from three. That would have put him sixth on the Wizards in that category this season but would have put him ahead of every power forward on the team.
Besides shooting guard Bradley Beal and small forward Martell Webster, the Wizards aren't a strong three-point shooting team. But point guard John Wall enjoys driving to the basket and now has a new weapon to dish the ball to outside for a quick three.
Wall, the team's leader, has said in the past that the team needed to add a stretch four and now Harrington gives them that option.
Harrington was also excellent at icing teams during his last year with the Nuggets, shooting 30 percent from three during the fourth quarter of games and 36 percent when the score margin was less than five, according to Basketball Reference.
Nenê is a great shooter from under the basket, but Harrington now gives them a change of pace to come in and score some quick points.
Encourage Harrington to Pass More
Harrington has always been a great shooting power forward, but has never been one to pass up on a shot and give the scoring opportunity to his teammate.
The 6'9" forward has averaged less than three assists per game every year since 2005 and has averaged less than one-and-a-half for the past five seasons.
Wall led the team in assists last season, followed by fellow point guard A.J. Price. Nenê was the next closest, averaging just less than three per game.
It's incredibly unlikely that Harrington is suddenly going to start averaging four assists per game, but an average over three would be a huge help to Washington and would take some pressure off of Wall.
If Harrington plays about 17 minutes per game and only averages one assist, he'll be taking too many shots and Washington is too talented at the other positions to not have the ball in Wall, Beal, Webster or Otto Porter's hands.
Harrington is best when he's taking a high volume of shots, but taking 15 shots per game would be crippling Washington, while passing the ball around to give Wall and Beal better looks would greatly improve their play over last season.