BOSTON (CBS) — Day 1 of the Patriots’ mandatory minicamp is in the books, and it appeared to be a day filled with ups and downs for the offense as the rainy weather wreaked havoc on players.

According to Bill Belichick, all 90 Patriots players were present and accounted for at Monday’s minicamp at Gillette Stadium in Foxboro. He didn’t seem too pleased to have to field questions about Tom Brady’s apparent concussion history, but for now the important thing is Brady was on the field doing Brady things – particularly to the team’s dynamic new wideout Brandin Cooks.

Here are some of the day 1 takeaways from Patriots minicamp, thanks to the assembled reporters who were present at Gillette:

Brady-to-Cooks connection heats up

Brady has a very shiny new toy in the 23-year-old Cooks, who has a chance to be as productive as any Patriots receiver in his first season in New England. The pair had some early success on Tuesday, connecting for four passes – more than any other receiver, according to the Boston Herald’s Jeff Howe.

Hat tip to ESPN’s Mike Reiss, who captured a perfect angle of this beauty of a corner pass from Brady to Cooks in the end zone:

More of this to come in the future? Tom Brady connects with Brandin Cooks as offense works against air (no defense). pic.twitter.com/rX32sI33LN — Mike Reiss (@MikeReiss) June 6, 2017

And the Patriots’ official Twitter account posted this pass over the middle:

As an added bonus, here’s some footage of Brady definitely not looking like he’s about to turn 40 years old:

If you just have to watch some video of Tom Brady on the field for the first day of #Patriots mandatory minicamp #WBZ pic.twitter.com/bEso3sIudi — Joe Giza (@JoeGiza) June 6, 2017

Cooks addressed Tuesday’s minicamp with reporters after practice:

If these early glimpses are any indication, Brady and Cooks will certainly be among the NFL’s most dynamic passing duos this season.

Bad day for ball security

Rain might be a nuisance for players at practice, but for Belichick it’s a good day to practice ball security. It apparently did not go very well, as Dwayne Allen dropped three passes while backup quarterbacks Jimmy Garoppolo and Jacoby Brissett each fumbled, according to Howe.

Dwayne Allen had 3 drops in team drills today. The Patriots had 9 as a team. Garoppolo and Brissett also had fumbles. — Jeff Howe (@jeffphowe) June 6, 2017

Brady led the way in the completion battle among QBs, but all three were hurt by the “many” drops.

Brady went 13-17 in 11s, Garoppolo 4-18, Brissett 8-13.

Brady 16-29 overall, Garoppolo 10-27, Brissett 19-26. Many drops in the wet cold. — Doug Kyed (@DougKyed) June 6, 2017

However, ball security wasn’t an issue for one surprising name …

Cyrus Jones doesn’t fumble

Jones committed some of the ugliest fumbles you’ll ever see in his rookie season, and that was with clear skies. You wouldn’t think he’d have a perfect day fielding punts in the misty rain, but according to Howe he was able to handle all eight footballs that were punted to him.

Cyrus Jones fielded all eight punts today in tough conditions. — Jeff Howe (@jeffphowe) June 6, 2017

It will be a whole different challenge for Jones to handle punts in real game action, but to avoid fumbling in such wet conditions is undoubtedly a step in the right direction for the second-year corner out of Alabama.

Duron Harmon appears to get injured

The Boston Globe’s Ben Volin tweeted that safety Duron Harmon, who signed a four-year extension with the Patriots in the offseason, “appeared to tweak something” during practice. His situation will be one to monitor as minicamp progresses.

Day 1 of Patriots minicamp in the books. Sloppy practice in the rain. Duron Harmon appeared to tweak something. Jonathan Jones worked as CB3 — Ben Volin (@BenVolin) June 6, 2017

Surely, everyone’s on the edge of their seat waiting for Belichick’s first injury report.