FOXBOROUGH, Mass. -- FOR A MOMENT it looked as though somebody else's blunder — as so often seems to happen around here — would bail out the Patriots. When Cardinals runner Ryan Williams let Brandon Spikes rip the ball away with a minute to play, and gave them possession on the cusp of field-goal range trailing by just two, it looked as though the Pats would somehow escape their home opener as winners.

But, in actuality, it was far more fitting for the game to finish the way it did: With a mistake by New England.

Officially, the game was lost when Stephen Gostkowski pulled a 42-yard field goal try without ever giving it a chance. It might have been the last and loudest, but it was merely one of the many misplays that collectively conspired to cost the Patriots and pin them with a 20-18 loss at Gillette Stadium.

“We shouldn't have been leaving it up to that particular situation,” quarterback Tom Brady said afterward. “We were fortunate to get that defensive turnover there late — we just came up short. We have opportunities to make plays and we're just not making them. Just too inconsistent.”

The day started with a mistake from the star quarterback himself, as Brady had his first pass of the afternoon batted up in the air and eventually intercepted. That led directly to an Arizona field goal. And it never really got better.

Tight end Aaron Hernandez went down with what is believed to be a high-ankle sprain on the Patriots' third offensive snap, and the attack seemed to struggle without one of their prime weapons, scoring only a field goal per period and averaging just four yards per play. There was no rhythm to what they were doing, and without Hernandez as an option, there at times seemed no rhyme to the playcalling in a clearly disrupted gameplan.

Another excellent week for the defense — which allowed just 3.2 yards per rush attempt, and yielded only one four-yard reception to all-world receiver Larry Fitzgerald — enabled the Patriots to survive their struggles through halftime, and was really the only reason New England held a 9-6 lead after the first series of the third quarter.

But on this day the Patriots just weren't good enough to take advantage of that fortunate position, repeatedly rejecting prosperity by continually shooting themselves in the foot.

When Brady made a beautiful throw of an out-pass on third and nine, and all he had to do was squeeze it for a first down, Wes Welker let the ball slip through his waiting arms. That forced New England to punt.

When they did, Nate Ebner was beaten easily off the edge, causing Zoltan Mesko's kick to be blocked by Quentin Groves. It went out of bounds at the Patriots 2, and three plays later the Cardinals had a 13-9 lead.

When the Patriots moved the ball to the Arizona 30 on the next series (certainly within Gostkowski's range), they tried running Danny Woodhead around the edge on third down, but lost nine yards and any opportunity to kick for points.

When they had the Cardinals facing second and 18 in their own territory, they yielded a 28-yard pass from Kevin Kolb to Todd Heap, then compounded it with a 15-yard Steve Gregory personal foul. Arizona had hit a snag offensively, but that play proved a spark, and six snaps later they were in the end zone celebrating a 20-9 lead.

Then, when Williams gave them life by fumbling when he could have effectively left them with an entire field to cover in 30 seconds, the Patriots repeatedly refused resuscitation. Rob Gronkowski was hit with a holding penalty that nullified Woodhead's 30-yard touchdown run. Then, after getting the ball to the 18 and deciding that was close enough, Gronkowski was called for a false start that added five yards to Gostkowski's attempt at the game-winner.

Then came the shank that hooked wide left and provided an appropriate conclusion to a week that was doomed to this destiny well before that ill-fated kick — and apparently even before kickoff.

“We didn't have a good practice there toward the end of the week, and I think it showed up today,” offensive guard Logan Mankins said. “We didn't play very well.”

“Just a lot of mental errors and things like that,” Welker answered when asked what he saw in practice leading up to the loss, “guys not doing their assignments and not doing their job.”

On the way to the Super Bowl last season, it was the Patriots' consistent ability to limit mental errors, to mind their assignments, to do their job that regularly left them in position to capitalize when their opponents messed up. They won games on discipline, on opportunism, on preparedness.

And when all three of those went away on Sunday, they lost. As much credit as the Cardinals may deserve for slowing the Patriots' potent offense, and for converting their chance to score, in the end the Patriots were in the same position they are so often. They had the ball. The opportunity was there.

If they had simply executed better on any number of occasions they would've been right where they needed to be. And even after they failed on all those earlier chances, they were still staring at a win in the final seconds thanks to Williams.

“He knows he almost cost us,” Arizona's Heap said of his running back. “When they missed the field goal, he was glad he wasn't the last mistake.”

It's typical of Patriots games that the team to make the last mistake loses.

Sunday, however, was the rare case that it was them.

Dave D'Onofrio covers the Patriots for the New Hampshire Union Leader and Sunday News. His e-mail address is ddonof13@gmail.com.