Oh, what might have been. It's the lament of a half dozen or so NFL teams every season, those whose formidable hopes were slashed by significant injuries to key players. History would be different if, say, Arizona Cardinals quarterback Carson Palmer (or even backup Drew Stanton) had been healthy when the 2014 playoffs began.

Who will own that lament in 2015? We have at least five candidates already. Let's evaluate the teams hurt most by injuries here at the season's midpoint.

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1. Pittsburgh Steelers

Record: 5-4

Analysis: The Steelers face a stiff fight in the AFC wild-card race after opening the season as a Super Bowl favorite. The list of injuries to elite and prominent players is staggering.

Sunday's game against the Cleveland Browns could mark their fifth game without quarterback Ben Roethlisberger (knee, foot). The Steelers are 3-2 with him and 2-2 without him in the lineup. Historically, their winning percentage has dropped from 66.9 in games he has played to 54.5 in games hasn't. Third-stringer Landry Jones would make his second start, in part because longtime backup Bruce Gradkowski (finger/shoulder) is on injured reserve and in part because Michael Vick (hamstring) is sidelined.

The team got only six games from tailback Le'Veon Bell (knee, suspension). Backup DeAngelo Williams has been productive, and the Steelers have actually averaged two yards more per play with him on the field than with Bell, but Williams is 32 years old and is now dealing with a foot injury. The offensive line lost All-Pro center Maurkice Pouncey (broken leg) and tackle Mike Adams (back) in the preseason and left tackle Kelvin Beachum (ACL) in Week 6.

The Steelers have played four games without linebacker Ryan Shazier (shoulder) and two games apiece with safety Will Allen (ankle) and defensive end Stephon Tuitt (knee) out. And they have lost at least one game (Week 4 against the Baltimore Ravens) because of a place-kicking odyssey that began with Shaun Suisham's preseason ACL tear and continued when replacement Garrett Hartley injured his hamstring prior to Week 1.

Put it all together, and it's amazing the Steelers have a winning record. But their injuries, combined with the Cincinnati Bengals' 8-0 start, have put them four games behind in the loss column in a division they should have been in contention to win. Their championship hopes might well be lost.

AP Photo/Matt Rourke

2. Dallas Cowboys

Record: 2-6

Analysis: The Cowboys have played most of the season without their two most important offensive players, and their defense has taken enough hits to leave it unable to compensate. The result: The Cowboys are alone at the bottom of the NFC East instead of at the top where most of us thought they would be.

All six losses came after quarterback Tony Romo broke his collarbone in Week 2. The return of receiver Dez Bryant (foot) in Week 9 didn't end the streak, and now Bryant is nursing a sore knee as well. With Bryant out for five games and totaling just 12 receptions all season, and the faltering Brandon Weeden/Matt Cassel duo at quarterback, the Cowboys don't have a wide receiver among the NFL's top 55 in catches or receiving yards.

We shouldn't be surprised. Since Romo took over the starting job midway through 2008, the Cowboys are 77-48 when he starts and 6-15 when he does not, according to ESPN Stats & Information.

There is a strong connection between health and defensive performance as well. The Cowboys lost their 2014 co-defensive MVP in the preseason, cornerback Orlando Scandrick, to ACL and MCL injuries. Rookie defensive end Randy Gregory (ankle) missed four games, linebacker Sean Lee has suffered two concussions and fellow linebacker Rolando McClain has been slowed by a hand injury among other ailments.

As a result, the Cowboys rank among the NFL's bottom third in defensive scoring (25.5 points per game) and defensive EPA, a measure of how a team performs relative to the NFL average. On both sides of the ball, the absences have been obvious.

AP Photo/Nick Wass

3. San Diego Chargers

Record: 2-7

Analysis: Instead of making a move in Mike McCoy's third season as coach, the Chargers have deteriorated into a disaster. They still have a healthy quarterback in Philip Rivers, but the team around him is nearly unrecognizable from the one that opened the season. Offensive line and receivers have been hit hardest.

Rivers faced massive pressure against the Bengals, Minnesota Vikings and Chicago Bears. In those games, all losses, the Chargers allowed a pressure rate of 26 percent and a total of 10 sacks.

That's no surprise given their personnel instability. Center Chris Watt (shoulder) made only three starts before being placed on injured reserve. Left tackle King Dunlap (concussion, ankle) has missed four games, as has guard Orlando Franklin (concussion, knee). The mess has left little room for Chargers running backs, at least for those who are left after Branden Oliver's season-ending turf toe injury. The Chargers rank No. 25 in the NFL in rushing yards before contact (2.22).

Rivers, meanwhile, has been throwing to a weakening group of pass-catchers. Tight end Antonio Gates (suspension/knee) has missed five games and backup Ladarius Green (concussion/ankle) has missed two. Receiver Keenan Allen suffered a season-ending kidney laceration in Week 8, and fellow starter Malcom Floyd departed with a labrum injury a week later. No. 3 receiver Stevie Johnson (hamstring) missed two games. Unless Floyd can play through his injury, the Chargers will return from their bye without a single wideout among the NFL's top 55 in receptions or yardage.

Ron Chenoy/USA TODAY Sports

4. Baltimore Ravens

Record: 2-6

Analysis: The Ravens have a pretty competitive team on their various injured lists.

They lost pass-rusher Terrell Suggs (Achilles) in the preseason and recently determined that tight end Dennis Pitta (hip) won't play this season. Defensive end Brent Urban (biceps) hasn't played yet. Neither has rookie receiver Breshad Perriman. Veteran receiver Steve Smith Sr. (Achilles) was sidelined after seven games and third-down running back Lorenzo Taliaferro played only three games before a foot injury ended his season.

Down so many offensive weapons, the Ravens' Total QBR this season is 44.3, the fourth-lowest in the NFL. Last season at this time, the Ravens ranked No. 11 with a team QBR of 68.1. It didn't help that left tackle Eugene Monroe (ankle) missed four games, either.

Defensively, with Suggs and Urban sidelined -- and defensive end Chris Canty (calf) inactive for four games -- the Ravens rank No. 19 in the NFL with a pressure rate against opposing quarterbacks of 25.2 percent.

In some cases, age has caught up with the Ravens. Smith is 36, Suggs and Canty are 33 and Pitta is 30. But it's hard to argue with the impact of across-the-board injuries on their roster.

AP Photo/Mike Roemer, File

5. Green Bay Packers

Record: 6-2

Analysis: It's tough to argue that a 6-2 team has been crushed by injuries, but the Packers' offense has been significantly different because of multiple ailments at receiver.

Jordy Nelson tore his ACL in the preseason, robbing the team of its best deep threat, and a sprained shoulder clearly limited fellow starter Randall Cobb in September. No. 3 receiver Davante Adams (ankle) missed three games and part of a fourth, rookie Ty Montgomery (ankle) has missed two and tight end Andrew Quarless (knee) has missed five.

As a result, the Packers are averaging 6.45 yards per dropback this season, a notable dip from their average of 7.15 over the same time period last season. Quarterback Aaron Rodgers is on pace for a nearly 400-yard dropoff in total yardage this season. At his current rate, he will fall short of 4,000 yards for only the second full season of his career.

The Packers also have gotten dangerously thin at cornerback during their two-game losing streak, one that has erased their lead over the Vikings in the NFC North. By the end of their loss to the Carolina Panthers, they were without Sam Shields (shoulder), Quinten Rollins (neck) and Casey Hayward (concussion). In those two games, opposing quarterbacks threw for a combined 637 yards and compiled an 88.6 QBR, the fifth-highest totals allowed by a defense over that period.