I've done some research on comparing pre-finale peformance of the final three teams.
It looks at each individual leg and how each of the three teams performed against each other. So in a Leg you get three data points, Team 1 beats team 2 and 3 and then team 2 beats team 3.
So for Season 28 we've had 11 pre-finale legs, so 33 data points, of which:
Tyler & Korey have beaten the other two teams 18 times out of 22 possible times = 82%
Dana & Matt have beaten the other two teams 13 times out of 22 possible times = 59%
Sheri & Cole have beaten the other two teams 2 times out of 22 possible times = 9%
(beat Tyler & Korey on Leg 7 and beat Dana & Matt on Leg 9)
This gives Sheri & Cole the worst pre finale performance versus the other two finalists of all finalists. The next worst is Dandrew at 10%, beating the other TAR13 finalists 2 times out of 20 (due to only 10 legs)
Full data attached for interest.
Rank Season Top 3 Teams No. of times beaten other two teams No. of legs before final leg % times beat other two teams pre final leg
1) 15 Meghan & Cheyne 18 11 82%
2) 20 Rachel & Dave 18 11 82%
3) 27 Justin & Diana 18 11 82%
4) 28 Tyler & Korey 18 11 82%
5) 13 Nick & Starr 16 10 80%
6) 6 Kris & Jon 19 12 79%
7) 16 Jet & Cord 17 11 77%

9 Eric & Jeremy 18 12 75%
9) 11 Dustin & Kandice 18 12 75%
10) 7 Rob & Amber 16 11 73%
11) 21 Trey & Lexi 16 11 73%
12) 24 Dave & Connor 16 11 73%
13) 10 Tyler & James 17 12 71%
14) 19 Ernie & Cindy 15 11 68%
15) 22 Bates & Anthony 15 11 68%
16) 25 Misti & Jim 15 11 68%
17) 5 Colin & Christie 16 12 67%
18) 14 Tammy & Victor 14 11 64%
19) 14 Margie & Luke 14 11 64%
20) 17 Jill & Thomas 14 11 64%
21) 25 Adam & Bethany 14 11 64%
22) 26 Hayley & Blair 14 11 64%
23) 2 Tara & Wil 15 12 63%
24) 4 Reichen & Chip 15 12 63%
25) 12 TK & Rachel 12 10 60%
26) 13 Ken & Tina 12 10 60%
27) 18 Gary & Mallory 13 11 59%
28) 21 Jaymes & James 13 11 59%
29) 28 Dana & Matt 13 11 59%
30) 1 Frank & Margarita 14 12 58%
31) 3 Ken & Gerard 14 12 58%
32) 8 Bransen Family 14 12 58%
33) 10 Rob & Kimberly 14 12 58%
34) 12 Ronald & Christina 11 10 55%
35) 7 Ron & Kelly 12 11 55%
36) 18 Kisha & Jen 12 11 55%
37) 19 Jeremy & Sandy 12 11 55%
38) 23 Jason & Amy 12 11 55%
39) 1 Rob & Brennan 13 12 54%
40) 3 Flo & Zach 13 12 54%
41) 4 David & Jeff 12 12 50%
42) 6 Freddy & Kendra 12 12 50%
43) 8 Linz Family 12 12 50%
44) 9 BJ & Tyler 12 12 50%
45) 20 Art & JJ 11 11 50%
46) 23 Nicole & Travis 11 11 50%
47) 24 Brendon & Rachel 11 11 50%
48) 5 Brandon & Nicole 11 12 46%
49) 15 Sam & Dan 10 11 45%
50) 17 Nat & Kat 10 11 45%
51) 22 Max & Katie 10 11 45%
52) 23 Tim & Marie 10 11 45%
53) 26 Jelani & Jenny 10 11 45%
54) 27 Kelsey & Joey 10 11 45%
55) 2 Chris & Alex 10 12 42%
56) 2 Blake & Paige 10 12 42%
57) 8 Weaver Family 10 12 42%
58) 17 Brook & Claire 9 11 41%
59) 26 Laura & Tyler 9 11 41%
60) 1 Joe & Bill 9 12 38%
61) 3 Teri & Ian 9 12 38%
62) 4 Kelly & Jon 9 12 38%
63) 5 Chip & Kim 9 12 38%
64) 11 Eric & Danielle 9 12 38%
65) 11 Charla & Mirna 9 12 38%
66) 7 Uchenna & Joyce 8 11 36%
67) 16 Dan & Jordan 8 11 36%
68) 16 Brent & Caite 8 11 36%
69) 18 Flight Time & Big Easy 8 11 36%
70) 22 Mona & Beth 8 11 36%
71) 12 Nicolas & Donald 7 10 35%
72) 19 Amani & Marcus 6 11 27%
73) 24 Caroline & Jennifer 6 11 27%
74) 9 Ray & Yolanda 6 12 25%
75) 14 Jaime & Cara 5 11 23%
76) 15 Brian & Ericka 5 11 23%
77) 27 Logan & Chris 5 11 23%
78) 6 Adam & Rebecca 5 12 21%
79) 10 Lyn & Karlyn 5 12 21%
80) 20 Brendon & Rachel 4 11 18%
81) 21 Josh & Brent 4 11 18%
82) 25 Amy & Maya 4 11 18%
83) 13 Andrew & Dan 2 10 10%
84) 28 Sheri & Cole 2 11 9%