The only number for Tyreke that has really slipped is his minutes. He played 37 minutes in his 2nd season, 34 in his 3rd, and 31 in his 4th. If we adjust his numbers for per 36 minutes, you will see that his points, rebounds, steals, blocks, and asst:to ratio has stayed about the same. You can check the numbers for yourself here:
http://www.basketball-reference.com/...evansty01.html
The one difference, however, is in scoring efficiency. Here is how his TS% has gone the past 3 years
Year 2: 48.2%
Year 3: 51.2%
Year 4: 55.8%
Now, to explain how he has become more efficient, we can look at hoopdata to see how he has adjusted his shot selection.
http://www.hoopdata.com/player.aspx?name=Tyreke Evans
The dumb zone is considered anywhere that isn't at the rim or the 3pt line, so that's 3-23 feet. Let's break down the number of shots he gets in the dumb zone per year
Year 2: 7.6
Year 3: 5.6
Year 4: 3.6
Meanwhile, shots at the rim and 3 point line have been pretty consistent
Year 2: 6.2 at the rim (59.8%), 2.6 3's (43.7 eFG%; 67.4% Assisted)
Year 3: 7.0 at the rim (64.6%), 1.6 3's (30.3 eFG%; 75.0% Assisted)
Year 4: 6.0 at the rim (63.2%), 2.0 3's (50.0 eFG%; 81.4% Assisted)
And one last thing, despite his FGA at the rim barely being the lowest of the 3 years, his free throw rate has continued to improve.
Year 2: 0.283 free throws per shot
Year 3: 0.286 free throws per shot
Year 4: 0.350 free throws per shot
So not only is Tyreke taking less shots in the dumb zone and more in the efficient spots of the court, he is taking less 3's off the dribble as seen by the assisted% go up, and that is a good thing for Tyreke since the 3 is already hard enough for him. What we see is that a player is playing smarter and more within himself, lowering his TO%, shooting better shots, and drawing more free throws. I expect this trend to continue as he gets more experienced and his understanding of the game continues to grow.