PDA

View Full Version : OPS+ (adjusted to player's ballpark)

Kingspoint
07-07-2009, 07:31 PM
From baseball-reference.com:

This value is calculated differently from the Total Baseball PRO+ statistic. I chose OPS+ to make this difference more clear. PRO+ as best I can tell is

OPS+ = PRO+ = 100 * ( OBP/lgOBP + SLG/lgSLG - 1)/BPF

Where lgOBP and lgSLG are the slugging and on-base percentage of a league-average player, and BPF is the batting park factor. This takes into account the difference in runs scored in a team's home and road games, so it doesn't depend on how good an offense or defense a team has.

My method is slightly more complicated, but I think it is more correct. The BPF is set up for runs and the way it is implemented in PRO+ applies it to something other than runs.

My method:

Compute the runs created for the league with pitchers removed (basic form) RC = (H + BB + HBP)*(TB)/(AB + BB + HBP + SF)

Adjust this by the park factor RC' = RC*BPF

Assume that if hits increase in a park, that BB, HBP, TB increase at the some proportion.

Assume that Outs = AB - H (more or less) do not change at all as outs are finite.

Compute the number of H, BB, HBP, TB needed to produce RC', involves the quadratic formula. The idea for this came from the Willie Davis player comment in the Bill James New Historical Baseball Abstract. I think some others, including Clay Davenport have done some similar things.

Using these adjusted values compute what the league average player would have hit lgOBP*, lgSLG* in a park.

Take OPS+ = 100 * (OBP/lgOBP* + SLG/lgSLG* - 1)

Note, in my database, I don't store lgSLG, but store lgTB and similarly for lgOBP and lg(Times on Base), this makes calculation of career OPS+ much easier.

Here are your current REDS w/ their Age, Plate Appearances and their OPS+. I included age because hitters get worse as they get past 28 and get better as they approach 27:

Age; Plate Appearances; OPS+

Wilkin Castillo: 25; 3; 251
Joey Votto: 25; 209; 175
Jonny Gomes: 28; 93; 165
Micah Owings: 26; 44; 122
Ryan Hanigan: 28; 163; 117
Laynce Nix: 28; 186; 105
Brandon Phillips: 28; 319; 104
Chris Dickerson: 27; 209; 102
Jay Bruce; 22; 323; 93
Jerry Hairston; 33; 278; 86
Ramon Hernandez; 33; 291; 82
Danny Richar; 26; 9; 56
Willy Taveras; 27; 293; 55
Paul Janish; 26; 82; 53
Alex Gonzalez; 32; 198; 46
Matt Maloney; 25; 5; 32
Darnell McDonald; 30; 44; 26
Edwin Encarnacion; 26; 89; 26

Here's each players' OPS+ for the last 5 seasons (along w/ Plate Appearances) so you can see their trends. Obviously, the younger players aren't going to have 5 years of OPS+ ratings in the Majors. Wilkin Castillo w/ 3 PA's in 2009 is not realistic, but others have a lot of at-bats to see a trend. I'll leave the current ages so you can see what their ages were for the seasons. All of this assumes no steroids, too. So, if Hairston or Hernandez or some of these other veterans were using steroids before the recent crackdown, then this year's numbers would reflect also a sharp decline. I used one extra year for Nix because he had PA's in consecutive years of 70, 12, & 13, but 400 two years before the 70. Alex Gonzales has no record for '08, and when you're older and don't play for more than a year, you decline even faster.

Age; (PA/OPS+) for each of last 5 years w/ 2009 being the last year shown:

Wilkin Castillo: 25; (34;60), (3;251)
Joey Votto: 25; (89;127), (589;124), (209;175)
Jonny Gomes: 28; (407;139), (461;95), (394;105), (177;73), (93;165)
Micah Owings: 26; (64;153), (62;97), (44;122)
Ryan Hanigan: 28; (11;95), (98;91), (163;117)
Laynce Nix: 28; (400;81), (240;70), (70;8), (12;-100), (13;-35), (186;105)
Brandon Phillips: 28; (9;-100), (587;88), (702;105), (609;92), (319;104)
Chris Dickerson: 27; (122;160), (209;102)
Jay Bruce: 22; (452;96), (323;93)
Jerry Hairston: 33; (430;82), (192;36), (184;42), (297;124), (278;86)
Ramon Hernandez: 33; (392;107), (560;111), (409;88), (507;86), (291;82)
Danny Richar: 26; (206;78), (37;29), (9;56)
Willy Taveras: 27; (635;75), (587;74), (408;89), (538;56), (293;55)
Paul Janish: 26; (89;36), (82;53)