As for Kyrie Irving versus Brandon Knight, Irving is a better shooter, a much better ball-handler, and a physically stronger player. Irving struggled shooting threes in this year's regular season, registering at .321, but that figure probably represents an aberration stemming from him coming off knee surgery. Entering this season, he was a career .390 three-point shooter, having shot .391 or higher in three of his first four seasons and reaching .415 in '14-'15. And Irving did shot .502 on two-point field goal attempts this season. His .555 career True Shooting Percentage compares favorably to Knight's .522 mark.
Knight is pretty weak going to his left (kind of like Jeremy Lin), whereas Irving is strong with both hands and can absorb contact while finishing, whether at the basket or from mid-range (defined traditionally as eight to fifteen or sixteen feet). Knight, conversely, seems to avoid contact or fall down too easily. Additionally, Irving squares his shoulders to the hoop while finishing or shooting, whereas Knight sometimes drifts or fades, and Irving possesses elite footwork. The "point guards" with the best footwork in the league may be Irving, Isaiah Thomas, Goran Dragic, Rajon Rondo, and Damian Lillard. (Yes, two of those guys played for the Suns not too long ago.)
Of course, Knight is an awful playmaker and an awful defender, so the following comments about Irving are not with regard to Knight. But according to Defensive Real Plus-Minus, Irving has ranked as one of the ten worst defensive point guards in the NBA in two of the last three seasons (among all points guards, not just starters), although he ranked in the middle of the pack in the year in between.
http://espn.go.com/nba/statistics/rpm/_/page/3/sort/DRPM/position/1http://espn.go.com/nba/statistics/rpm/_/year/2015/sort/DRPM/position/1http://espn.go.com/nba/statistics/rpm/_/year/2014/page/2/sort/DRPM/position/1As a playmaker, meanwhile, Irving is mediocre at best. He is capable of making good passes, but his interest in involving teammates ranges from minimal to sporadic. He is barely a point guard—really more of a shooting guard with a great handle, and he sports a career assists-to-turnover ratio of 1.99:1.00 (2.01:1.00 this past season). LeBron James serves as the Cavaliers' point guard as much as Kyrie Irving, which minimizes Irving's weaknesses in that area for the foreseeable future. But without James, I am not sure that Irving could lead a team to any place of note without another major offensive player who will make the game easier for teammates.
Of course, many "point guards" these days are guards with a great handle and the mentality of a shooting guard. Stephen Curry, while capable of making some nifty passes, also barely reached 2.00:1.00 in terms of his assists-to-turnover ratio this past season—his playmaking proved mediocre for a point guard, as he basically threw away too many passes. Of course, when you average a league-leading 30.1 points on a league-leading .669 True Shooting Percentage—in some senses the greatest scoring season ever by a guard—some flaws as a playmaker can be excused and overlooked. But Curry's scoring has not been quite as great in the playoffs (he is shooting .445 from the field, down nearly fifty points from his .504 in the regular season), and his playmaking has proved poor. After his 1-assist, 4-turnover performance in Game Six at Cleveland, Curry's assists-to-turnover ratio in the 2016 playoffs now stands at 1.28:1.00, which is just awful for a "point guard" playing major minutes. And one can see it on the court: he forces passes constantly, and his passes are routinely deflected or intercepted. Curry tries to throw passes into tiny windows, but there are two problems with how he attempts to do so. First, you have to be able to make those fine reads about when the window is small yet plausible and when the window is too small. Curry struggles in that regard, especially in the face of playoff-type defensive pressure and congestion. Second, to throw passes through small windows, you have to be able to throw seeds—seeds that are still catchable, often through a combination of velocity and backspin, not to mention precision. The best that I have ever seen in that regard are probably the trio of Magic Johnson, John Stockton, and Kevin Johnson, who—not coincidentally—constitute the only three players in NBA history to average at least 10.0 assists per game started. The best right now are probably Rajon Rondo and John Wall. But Curry tries to throw passes that are way too flaccid and lackadaisical into extremely tight windows, with the result being that the windows regularly close before his passes arrive, yielding deflections and steals. Curry's career assists-to-turnover ratio in the playoffs is an Eric Bledsoe-like 1.74:1.00.
So Irving is far from the only problematic playmaker out there, to be sure. But for as great of a shooter and scorer as he can be, he is not Stephen Curry in that regard, either. One aspect that aided his efficiency in Game Five, though, is that Irving simplified the game. Sometimes his greatest asset—that authoritative ball-handling ability—can become a liability, as there were times earlier in the series where he would dribble up a storm and sometimes seem to dribble himself into worse shots that what he had previously enjoyed.