Davis’ component-power score is only projected to be a +35 (he says “only”), after putting up a surprising 50 last year.
His three-year line for power going into 2014 is 29, 27, 50. I did a quick search for players who
1) had 250 PA each across a four season span
2) were 26-30 in the fourth season (Davis will be 28 this year);
3) averaged at least a +15 power in the first two years
4) was at least 15 runs better than each of the first two years
That gave us this list:
yr4 age4 pow1 pow2 pow3 pow4 pow4-3
Jack Cust 2008 29 9 26 43 41 -2
Juan Diaz 2001 27 20 12 39 31 -8
Jim Gentile 1962 28 19 26 51 25 -26
Willie Horton 1969 26 22 26 41 21 -20
Todd Hundley 1997 28 19 20 43 36 -7
Adam LaRoche 2007 27 17 15 33 14 -19
Joey Meyer 1988 26 22 21 43 17 -26
Jai Miller 2012 27 20 19 38 16 -22
Kevin Mitchell 1990 28 16 18 54 32 -22
Mike Napoli 2009 27 22 15 39 19 -20
Dave Nicholson 1969 29 19 17 37 20 -17
Gene Oliver 1962 27 20 14 35 10 -25
David Ortiz 2004 28 17 17 32 34 2
Carlos Pena 2008 30 24 14 52 31 -21
Mark Reynolds 2010 26 20 22 39 34 -5
Tony Solaita 1976 29 22 19 54 15 -39
Gorman Thomas 1979 28 22 28 48 55 7
Jason Thompson 1982 27 12 21 42 30 -12
Jim Wynn 1968 26 15 16 35 29 -6
Only 2 out of 19 players (David Ortiz and Gorman Thomas) managed to up their power score yet again in the fourth year. The mean change from year3 is -15; the media change is -20. After averaging 42 in the boom year, they averaged a (still repectable, and still better than the first two years) 27 in the fourth year.