Sayth
I looked into calculated fields, a topic I've never been much good with, but couldn't find anything.
I also looked into Value Field Settings... where you have the option of Show Values As.
I've used that in the past it's always been a bit hit and miss though.
I tried with the example workbook but couldn't come up with anything, though I only tried a few options.
Like I said you could try GETPIVOTDATA, here's how I did it.
Formula L5 : GETPIVOTDATA("average of career",A4,"number", 1)
Formula L6 : =GETPIVOTDATA("average of career", A4,"horse", K6 )-$L$5
Values K6:K12 : horse's names
This was the result which appears to match yours.
<TABLE style="WIDTH: 150pt; BORDER-COLLAPSE: collapse" border=0 cellSpacing=0 cellPadding=0 width=200><COLGROUP><COL style="WIDTH: 88pt; mso-width-source: userset; mso-width-alt: 4278" width=117><COL style="WIDTH: 62pt; mso-width-source: userset; mso-width-alt: 3035" width=83><TBODY><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; WIDTH: 88pt; HEIGHT: 15pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl63 height=20 width=117></TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; WIDTH: 62pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl64 width=83 align=right>269474.5714</TD></TR><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; HEIGHT: 15pt; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=20>DAYTONA BEACH</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl63 align=right>-$103,244.57</TD></TR><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; HEIGHT: 15pt; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=20>ENZEDEX EAGLE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl63 align=right>$71,735.43</TD></TR><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; HEIGHT: 15pt; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=20>GOD'S HAND</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl63 align=right>$20,405.43</TD></TR><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; HEIGHT: 15pt; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=20>Hidden Wonder</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl63 align=right>$123,797.43</TD></TR><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; HEIGHT: 15pt; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=20>STREETFIGHTER</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl63 align=right>$55,815.43</TD></TR><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; HEIGHT: 15pt; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=20>SUPERIOR INSTINCT</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl63 align=right>-$140,814.57</TD></TR><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; HEIGHT: 15pt; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=20>TRIPLE ELEGANCE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl63 align=right>-$27,694.57</TD></TR></TBODY></TABLE>
Obviously having to repeat the names isn't ideal, I'm going to look further into the other options.