Time of Possession
Great point. Cowboys ranked 26th in TOP late in close losses since 2011 (I used 2011 to avoid the very time-consuming exercise of having to filter out the non-Romo games in 2010). Interestingly (and pathetically), they ranked 26th in the average length of offensive possessions and 26th in defensive as well. It's easy to see why the offense ranked 26th:
First Down Percentage Rank
pass: 4th
run: 28th
Only 3 teams were better at getting first downs via the pass, and only four were worse via the run. That's why in the OP I included first downs by run and stated that the most important run stat late in close games is how well you move the chains. If this offense is to improve its TOP in these situations, it's going to have to run the ball a lot better.
That said, before anybody gets too carried away with pass/run's effect on the defense, I also compared TD% allowed after punts with TD% allowed after kickoffs since 2010. When the opponent's possession began after a punt, the Dallas defense ranked 27th. When it began after a kickoff (either to start the 1st or 2nd half, or following a Dallas scoring drive) the Cowboys defense ranked 32nd. So, while any defense should play better given more rest, the "rested" Dallas defense has actually played worse, relative to the rest of the league's defenses in the same situation. In short, the overall issue with the defense hasn't so much been a lack of rest as it has been a lack of defense.
Strength of Opposing Defense
I don't know how closely you read the OP, but it's quite situation-specific (4th qtr or OT of losses, score + or - 8 points). All the turnovers, TD, and anything else listed occurred in that precise situation, and the entire point was to look at "how games are being lost." But the middle part of your quote is a useful suggestion.
These are all the defenses Dallas has faced with Romo late in close losses since 2010 (the defenses against which the stats in the OP were compiled). Each defense is listed with its passer rating allowed and where that rating ranked among the league's defenses that year. Below that, you'll find Romo's line in the loss(es) against them that year (att, comp, yds, td, int, sk). As in the OP, sacks count as attempts, and all QB turnovers count as INT in the rating.
2010 Commanders 89.6 (24th)
9 of 17 104 0 0 0
2010 Bears 74.4 (3rd)
Romo 5 of 8 66 0 0 0
2010 Titans 86.4 (21st)
9 of 18 111 1 2 0
2010 Vikings 86.4 (22nd)
7 of 11 83 1 1 0
2011 Jets 69.6 (3rd)
5 of 13 128 0 2 1
2011 Patriots 86.1 (20th)
9 of 15 106 0 0 0
2011 Lions 82.1 (12th)
7 of 11 45 0 1 1
2011 Cardinals 82.5 (13th)
10 of 14 107 0 0 1
2011 Giants 86.1 (21st)
7 of 11 186 2 0 0
2012 Ravens 80.6 (11th)
11 of 17 101 1 0 1
2012 Falcons 77.1 (5th)
5 of 6 69 0 0 0
2012 Giants 88.7 (20th)
12 of 22 117 0 1 1
2012 Commanders 87.0 (18th)
1 of 4 14 0 1 0
2012 Saints 93.8 (28th)
6 of 9 80 1 0 0
2013 Chiefs 78.5 (7th)
8 of 16 69 0 1 1
2013 Chargers 96.4 (28th)
4 of 5 28 0 0 0
2013 Broncos 84.5 (17th)
6 of 10 144 2 1 1
2013 Lions 85.0 (19th)
3 of 4 118 2 0 0
2013 Packers 95.9 (25th)
8 14 72 1 2 1
Romo vs...
top 11 (5 games) 34 of 60 433 1 3 3 64.1
middle 10 (9 games) 64 of 109 948 7 6 4 85.7
bottom 11 (5 games) 34 of 56 367 3 3 1 75.5
TOTAL 132 of 225 1748 11 12 8 76.7
Very low rating, as with all these QB in these games which, after all, were all lost. No "huge variance" issue to be noted, considering there's about a 10-point rating difference between the best and worst defenses he faced.
Remember that Romo's rating (as seen in the OP) is the best of the top QB in these situations, meaning that whatever those guys may have gained against the top defenses, they lost right back (and then some) against the other defenses they faced. But there's the breakdown you were looking for.
Leading vs. Trailing
I'll take "winnable" to mean one-score games (+ or - 8 point margin). We already know the defense ranked last among the 10 QB's teams covered in the OP in TD% allowed late in close losses. We also know that the offense was among the league's best in these situations. I'll break down these losses further, based on score. Again, these are rankings since 2011 (for reasons stated above) out of all 32 teams.
4th Qtr or OT, trailing or tied
Offense TD%
1. Patriots
2. Cowboys
3. Broncos
4. Raiders
5. Giants
Defense TD% Allowed
28. Rams
29. Packers
30. Bears
31. Cowboys
32. Panthers
4th Qtr or OT, leading or tied
Offense TD%
1. Titans
2. Cowboys
3. Bears
4. Falcons
5. Broncos
Defense TD% Allowed
28. Cowboys
29. Rams
30. Patriots
31. Panthers
32. Bears
This is the rank in the percentage of drives that resulted in a touchdown. Late in close losses, offensively Dallas was 2nd best, whether leading or trailing. Defensively, the Cowboys were 28th when leading and 31st when trailing.
I hope that gives you a clearer picture.