FOXBOROUGH, Mass. -- Let’s start with some of the important disclaimers: It’s still early … there is a history of improvement as time progresses … losing a captain to injury is seldom easy … and they’re relying on an undrafted rookie, fourth-round draft pick, and a player who arrived via trade just three weeks ago.

OK, now that's out of the way, here’s the question: What’s up with the New England Patriots' defense?

Sunday’s 36-33 win over the Houston Texans -- a result that easily could have gone the other way if not for Tom Brady’s magical comeback effort -- highlighted some concerns on defense. The unit is putting a lot of pressure on Brady and the offense, with Texans rookie quarterback Deshaun Watson totaling 301 passing yards as he bobbed and weaved his way through defenders to add 41 rushing yards on eight carries while extending other plays in the pocket.

Safety Devin McCourty noted how Watson’s elusiveness put stress on the defense, while pointing out that the quarterback coming to town this Sunday, Cam Newton of the Carolina Panthers, has similar ability.

“We’ve got a lot of work because that guy can do that better than anyone in the NFL,” McCourty said of Newton. “That’s something, obviously, we’ve got to keep working on.”

Defensive coordinator Matt Patricia, who has been trying to put the puzzle together without linebacker/captain Dont’a Hightower (knee injury), is getting by with a game plan-specific approach as the team is figuring out what it has personnel-wise (and if that personnel is good enough).

That includes relying on undrafted defensive lineman Adam Butler, fourth-round pick Deatrich Wise Jr., as a top pass-rusher and newly acquired Cassius Marsh as an end-of-the-line player.

In the opener against the Kansas City Chiefs, Patricia utilized primarily a dime package (six defensive backs). Then in the second week at the New Orleans Saints, it was more of a “big nickel” game (five defensive backs, with three safeties and two cornerbacks).

And against the Texans, it was a base defense game, with the Patriots mostly playing what could be called a 5-2 or 3-4 alignment, depending if one referred to Trey Flowers and Marsh as defensive ends or outside linebackers.

The plan seemed fairly obvious: Get heavier at the line of scrimmage and don’t let the Texans get the running game going to make life easier on Watson. And in the process, don’t allow Watson to win with his legs, either.

The Patriots were competitive against the run (Houston finished with 32 rushes for 125 yards), but it was their work against the pass that was more alarming. Credit to Watson, of course, but the Patriots could have made it much harder on him than they did.

The secondary, in particular, has almost every starter from 2016 returning and added big-ticket free-agent signing Stephon Gilmore. But the resistance wasn’t consistently there.

The Texans had five passing plays of 20 yards or more in the game, as the Patriots have now surrendered 13 passing plays of 20 or more yards through three games. That puts them on pace for 69 this season after allowing 44 in 2016.

Maybe the Panthers and Newton, who haven’t been lighting up the scoreboard, are the right opponent to help the unit tighten some things up.

“[Patriots coach] Bill [Belichick] said it best after the game. We’ve got a lot of work to do defensively,” McCourty said. “It doesn’t get any easier next week with Cam Newton. The good thing is we’ll be highly critical of how we played against Watson because we’re going to see something similar Sunday.”