Brad Stevens is finding success with small-ball lineups for the Boston Celtics

Maybe Brad Stevens should've inserted Marcus Smart into the starting lineup sooner than he did, because the Boston Celtics are flying high in two games with their new point guard.

Smart has played a team-high 78 minutes in the last two games and the Celtics have a plus-13 net rating with him on the floor. But in the 18 minutes the energetic rookie has taken a breather on the bench, Boston has a cringeworthy minus-42.9 net rating.

But not all of the credit should go to Smart for Boston's two-game winning streak, because Stevens has brilliantly utilized small-ball lineups with only one big man on the floor. Stevens has gone to a lineup with "four smalls" for 45 minutes and the Celtics have a 122.5 offensive rating and 109.6 defensive rating.

Here are all six small lineup combinations used this week with some key statistics detailing their effectiveness:

The top grouping of Marcus Smart, Marcus Thornton, James Young, and Jae Crowder has been a driving force in each of their last two wins, with 21 minutes played and a net rating of plus-41.9.

This lineup is suffocating teams defensively, with 9.1 steals per 48 minutes, which would rank in the top 5 of the NBA. Smart and Crowder are certainly known for their defense, but both Thornton and Young have also brought lots of vigor.

Boston is able to comfortably switch with almost every player on the floor, just like they do at the start of the possession on a 4-1 pick-and-roll in the video above. Crowder switches onto the point guard and Smart denies the power forward from establishing low post positioning. New York runs some lazy actions, but at the end Boston plays highly aggressive defense, forcing them into a low percentage field goal attempt.

Stevens tried going with similarly small lineups early in the season, but they were very ineffective and he eventually went away from them; this is likely because Boston lacked the proper personnel to use them.

Now with Crowder, Boston has a feisty wing who isn't afraid of getting his nose dirty with the big boys down in the paint -- which is the polar opposite of Jeff Green, who is arguably one of the softest rebounding forwards in the league -- and he also has the quickness to defend many guards. The Celtics hope that Young can develop into a similar versatile defender, though he is years away from reaching that level.

Offensively, these small-ball lineups benefit from floor spacing and perimeter shooting. All six lineups are shooting a combined 12-for-30 from three-point range and are able to open up the paint for driving lanes.

In the two clips above, Boston's spacing causes problems for New York's defense, since they must crash the paint whenever penetration occurs. This opens up breathing room near the arc, like it did in both plays. On the second clip, the double screen action for Evan Turner actually frees up three players, Brandon Bass on the roll, and both Crowder and Bradley from three.

Boston runs their regular read-and-react offense regardless of who's on the floor, so these types of plays are nothing new, but the personnel certainly does allow for more consistent spacing, since of Boston's bigs, only Kelly Olynyk has consistent success from behind the arc. And right now he is unfortunately hurt, which is another reason why Stevens is basically forced to go small right now.

Every other small-ball lineup has a tiny sample size, but if there is any reason for concern it's that they have not been as successful, with a cumulative minus-12.5 net rating (114.1 offensive rating and 126.5 defensive rating). It's possible that Stevens' small-ball lineups are purely matchup-dependent, and that those weren't the ideal play within the game, so it's worth monitoring their production next week against teams with larger front courts like Milwaukee and Atlanta.

Once Olynyk returns from his injury it'll be interesting to see if Brad Stevens continues to run with small lineups, but if their overall success continues then he will have to. They bring so much tenacity on defense and that creates easy transition opportunities for the Boston Celtics, which is a necessary ingredient if they have any hopes of reaching the NBA Playoffs.

Follow @KevinOConnorNBA