The Indianapolis Colts have been one of the lousiest teams in the NFL. By our power ratings, no one has been worse.

You would not know it if you stopped watching games at halftime. For the first two quarters, the Colts look like an above-average team.

The second two quarters, however, are an abject trainwreck.

The Colts have trailed at halftime in only one of their six games this season, and that was a game Scott Tolzien started. They were tied at the break in Week 5 but held a lead after two quarters in their other four contests. Overall, they have a plus-6 scoring differential in the first half.

This isn't something we'd be talking about if it were not for a ghastly minus-82 scoring margin after the break.

Things have been especially pronounced in the fourth quarter, where the Colts have blown leads three times (in losses to the Cardinals and Titans and an overtime win over the 49ers). In the final period alone, Indianapolis has been outscored 85-22.

An Inability To Finish

In Week 2, the Colts defense faced a third-and-20 from its own 18, defending a 10-point lead with 8:55 remaining. Per our win probability model, Indianapolis had a 93.6% chance to hold on for the victory. Instead, the Colts allowed a 22-yard completion on a play during which they also roughed the passer. The following play, they allowed a 45-yard touchdown pass.

The Indianapolis offense was then held to a three-and-out, Arizona tied the game on its next possession and went on to win in overtime.

Indy's chokes were less drastic in their two primetime losses, but still involved the Colts failing to take advantage of a halftime lead. Their peak win expectancy in its Week 4 loss in Seattle was just under 54% when it took a 15-8 lead into halftime.

In Week 6, we gave Indianapolis a 74% chance to beat Tennessee after John Simon returned a Marcus Mariota pass 26 yards for a touchdown that put the Colts ahead 19-9 early in the third quarter.

It was more scoring than the Colts offense would do in the second half, but the Titans still trailed 19-18 going into the fourth quarter before completing their comeback.

The story has even been similar in the Colts’ wins. As mentioned, they needed overtime to beat San Francisco despite a 14-point fourth quarter lead, and they even flirted with disaster at home against the Browns in Week 3.

In that game, the Colts led 28-7 in the second quarter and 31-14 in the fourth, but still needed a late onside kick recovery to secure the victory.

The Numbers Behind the Collapses

The Colts’ first-half numbers will not blow you away but in the aggregate, they have been better than their opponents'. They are 9th in the NFL in first-half points per game (12.5) and tied for 17th in points allowed (11.5).

In the second half, they are 31st in scoring (6.8) and dead-last in points allowed (20.5).

These splits also hold up on a play-by-play level, when looking at yards per play, Net Expected Points and Success Rate. To learn more about the latter two numbers, check out our glossary.

For context, the league averages for yards per play, NEP per play, and success rate are, respectively, 5.3, 0.03 and 43.1%. The gap between Indy's NEP per play production by half is almost as large as the gap between 2nd-ranked New England and 32nd-ranked Miami.

Much of the gap is on the passing game -- though Indianapolis’ rushing efficiency does plummet from below average to atrocious from one half to the next.

Jacoby Brissett has been an above-average passer in the first half (48.9% success rate, 0.23 NEP per drop back) but one of the worst quarterbacks in the league after halftime (34.8%, -0.19). The NFL average success rate on drop backs is 45.3%, while teams are averaging 0.06 NEP per pass play.

The picture is slightly prettier on defense, as while the results have obviously been terrible, a comparatively small number of big plays have been the main issue.

Against the pass, the Colts’ success rate actually improves in the second half (from 46.0% to 49.1%), but it has allowed 0.31 NEP per pass in the second half (0.05 more than in the first). The reason is a spike in huge chunk plays through the air. The Colts have allowed a league-high 34 passes of 20 yards or more, and 20 of them have come in the second half.

The run defense has had a similar problem, as it has allowed a steady 29.6% success rate on the ground in the first half and a mark of 28.42% in the second. However, its yards per carry average balloons from 3.6 to 4.5 because of big plays -- the Colts have allowed just 5 runs of 10 or more yards in the first half (6.8% of opposing carries), but 12 such runs the in the second (12.8%).

The silver lining for the Colts is that Success Rate tends to be comparatively stable while explosive plays allowed are more fluky -- over the past five seasons, yards per completion in one season correlated with itself in the next at only 0.25, with 1 implying a perfectly linear relationship and 0 implying no relation. Contrast this with completion percentage, which correlated with itself at 0.52 from one year to the next.

Big play defense on the ground was similarly inconsistent last year, as measured by the percentage of rushes that gained 10 or more yards. The worst five teams by this measure in Weeks 1 through 8 ranked 16th, 20th, 12th, 32nd and 9th over the rest of the season, per SharpFootballStats.com.

The Blame Game

It is hard not to put at least some of the blame here on head coach Chuck Pagano. Pagano has often left much to be desired in terms of his fourth-down approach and usage of challenges and timeouts. This apparent lack of second-half adjustments is another thing that has infuriated Colts fans.

Then again, this dramatic decline in play from one half to the next has not been a hallmark of Pagano’s time in Indianapolis. For most of his head coaching career, there was not much of a split and the last time there was a drastic one, it involved the Colts struggling in the first half.

If we look at Success Rate rather than points, the same pattern is evident -- the Colts played much better in the second half in 2013, somewhat worse in the second in 2014 and 2015, and better in 2016.

Again, Pagano has hardly covered himself in glory in 2017, but the second-half collapses may not be an issue that as is simple as the coach not making adjustments.

The Colts have a young and inexperienced roster, which also does not help matters and could explain at least some of the big play issues -- a young player is presumably more susceptible to a blown assignment than a veteran, for example.

It is also worth noting sometimes splits are not actually measuring anything more than random coincidences.

Whether it is the coaches, players, randomness or the combination of the three, these second-half collapses have a put a massive dent in the Colts’ postseason chances. The preseason hope that Indianapolis would stay above water against the easy part of its schedule until Andrew Luck returns now looks like fantasy -- we give the Colts just a 1.5% chance of making the playoffs.

Maybe things will improve in the second half of the season. But the 2017 Indianapolis Colts aren't so hot with second halves, so let's not hold our breath.