The Lakers made a really smart move (pun intended). 
Marcus Smart will strengthen their defense and can contribute around 10 points per game on average. With a 2-year $11 million contract, he won't take up much salary cap space either. The fact that Luka specifically wanted him is also important. After signing Ayton, this is another very solid addition. The Lakers put themselves in a position to be real contenders again.
With Finney-Smith out for the Lakers, they need a primary defender that can defend from 1-4, and Smart can do it still. Marcus Smart will strengthen their defense and can contribute around 10 points per game on average. With a 2-year $11 million contract, he won't take up much salary cap space either. The fact that Luka specifically wanted him is also important. After signing Ayton, this is another very solid addition. The Lakers put themselves in a position to be real contenders again.The problem when he's on Memphis is that, they want him to be a playmaker, and at the same time, defender, and he can't do it because he's a defense-first type of player that's why he got out of the rotation on Memphis, and in Washington as well. Now with lots of offensive-minded players in the Lakers, he don't need to focus more on offense, but more on defense. What's also good is that, the Lakers don't need to spend that much money to get him. For 2 years worth $11M, that's a friendly deal already. Let's see though if he can redeem himself this time now that he's on another team.
Now are the Lakers a title contenders after this acquisition? Nope I don't think so because I look at their depth and it's still bad compared to other title contenders on the West like the Thunder, Nuggets, and even the Rockets. They can clinch the playoffs though. I wonder who they will be getting though to improve their bench.