By Matt Dolloff, CBS Boston

BOSTON (CBS) — The performance of the Patriots defense – for the whole season, not just on Sunday night – has to be a major concern. If the Pats do not end up winning their fifth Super Bowl this season, it appears that the defense could be the reason why.

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The unit as a whole had trouble at all three levels on Sunday night against the Seattle Seahawks. They could not generate good-enough pressure on Russell Wilson, nor could they even serviceably cover receivers in the secondary. But another big issue for the Patriots defense over the course of the season has been an alarming lack of takeaways.

Through 12 weeks, the Patriots are 26th in the NFL with just nine total takeaways. They’re in the same territory as some of the worst defenses in the league in that category, like Chicago, Jacksonville, and the New York Jets. It’s worth mentioning that Seattle is just ahead of the Patriots with 10 total takeaways, but no reasonable person would argue that those two defenses are on the same level, at least in terms of personnel.

As far as turnover differential, the Patriots are tied for 13th in the NFL at plus-1, mostly thanks to Tom Brady’s impeccable ball security (neither Jimmy Garoppolo nor Jacoby Brissett threw an interception, either). Seattle is seventh in the NFL with a plus-4 turnover differential.

The stat is a good indicator of success; six of the 12 current playoff teams are in the top-10 in the league in turnover differential. The 7-2 Kansas City Chiefs lead the league with a superb plus-14 differential, thanks to a league-leading 13 defensive interceptions.

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What’s causing the Patriots’ lack of takeaways on defense? Defensive coordinator Matt Patricia was asked about the problem during his Tuesday conference call. He stopped short of blaming his own defensive schemes, but did imply that the defense has at times lost focus while on the field.

“I don’t know if I’d really go with the scheme part of it as much as just, you know, there are definitely opportunities in the game where those turnover opportunities come up whether the ball is out, in the air, or whatever the particular case may be. We just have to make sure we come up with those opportunities. … Certainly there have been some opportunities in the game that we’ve got to do a better job of taking advantage of. A lot of that is, sometimes it’s focus, concentration or whatever the case may be. We’ve got to do a better job of staying on those situations when they come up and being alert and aware.”

The Patriots have certainly not lacked opportunities to take the ball away, especially when it’s in the air. They’ve allowed the sixth-most passing attempts in the league with 352, yet have only five interceptions to show for it. The problem with Patricia’s comment is that some of that is scheme-related, as the Patriots secondary often plays to keep the ball in front of them, opting to allow short and simple passes and tackle the ball carrier to prevent big plays. “Tackling and turnover are something we emphasize,” Patricia added in his conference call.

Except on Sunday night, not only did the Patriots not come close to forcing a takeaway, they couldn’t even prevent the big plays. They allowed five catches of at least 20 yards and three of at least 36 yards. That kind of defense is borderline useless.

The Patriots have had a turnover problem for most of the season, but it was exacerbated on Sunday night when the defense failed to produce a takeaway while Tom Brady threw his first interception of the season and Julian Edelman lost a fumble. The lack of playmaking on the defense could easily be attributed to a lack of dynamic playmakers on that side of the ball. The offseason trade of Chandler Jones (two fumble recoveries, one against the Patriots in Week 1) and the puzzling mid-season trade of linebacker Jamie Collins, who made two of the Patriots’ five interceptions on the season, have magnified the problem.

Whatever the issue is with the Patriots’ lack of takeaways, it’s something that is simply going to have to improve, especially if the Patriots’ ball security on offense does not. The defense can’t continue to be as porous as it’s looked over the course of the season if the Patriots want to go to Houston in February, let alone leave with a fifth Lombardi Trophy.

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Matt Dolloff is a writer for CBSBostonSports.com. Any opinions expressed do not necessarily reflect that of CBS or 98.5 The Sports Hub. Have a news tip or comment for Matt? Follow him on Twitter @mattdolloff and email him at mdolloff@985thesportshub.com.