Eli Manning was pretty abysmal last year, as far as NFL quarterbacks go. There wasn't really any aspect of his game you can point to that said otherwise. He turned the ball over more than any other quarterback. He wasn't throwing downfield well, shown by his 21st-ranked yards per attempt. And he was 32nd in completion percentage. There are only 32 starting quarterbacks in the NFL. That is not good.

Then offense coordinator Ben McAdoo came along, formerly the quarterbacks coach of the renowned Green Bay Packers. He was theoretically supposed to bring many of the same concepts that make Aaron Rodgers one of the NFL's top quarterbacks and apply those to Eli Manning and New York's offense. 

McAdoo brings a quick-hitting offense to New York that emphasises quick quarterback progressions and decision making. But many of the playcalls don't even require decision making that is too complicated--rather, receivers are often schemed open, making the read easy for the quarterback to make so long as he knows the offense and is accurate with the football.

One of these concepts is this one shown below. This idea is a staple play of what the Packers and now Giants do, and can be very effective when everyone does their job. 

The inner-most receiver, sometimes the tight end, or in this case an inside receiver, runs directly into the flat. Meanwhile, the outside receivers don't even go out on routes, and attempt to block their defenders downfield to create space for the guy in the flat. When you have receivers willing to block, this play is very effective against the blitz and in short-yardage situations. This "downfield screen" (I like to call it) is almost an extension of the running game. 

This next example highlighted is a very similar concept to the downfield screen, but it basically replaces the receiver with the running back. As you can see, the receivers on the offense's right side (circled) don't even try to go out on routes--they rather block their defenders right away downfield to create an alley for the running back, who this play is designed for. For some reason, Manning tries to throw to the isolated receiver circled in blue instead, but his running back had a lot of room had Manning chosen to throw his direction.

The Giants offense also runs variations off this concept. In the next play below, you initially see similar movement to the play highlighted above, with the slot receiver running to the flat and the outside receivers getting downfield to create space. But instead of blocking like the defenders have been set up to expect, Rueben Randle in this case runs a quick slant for a first down. Running different plays out of the same formations and using similar ideas is an excellent way to keep the defense on its heels.

This next play is a very similar concept, with the outside receiver running a rub route with the slot receiver. The slot receiver's defender is forced to go downfield and around the traffic created by the outside receiver, naturally creating space for the slot receiver. This actually wasn't the original playcall--Eli audibled to this play when he saw Atlanta playing man coverage before the snap, which is something I like a lot about this offense. The plays aren't overly complex, but are very effective, and the freedom Manning has shows that he is as sharp as ever from a mental standpoint. 

The below (crudely drawn, sorry) diagram is a play the Giants like to run a lot against Cover 3. The two outside receivers run comeback routes, while the two inside receivers run down the seam. This creates space underneath for the running back as a checkdown option. The comebacks should be there for the taking against a cover 3 defense, since the cornerbacks often play bail technique so the receivers can't get behind them. Meanwhile, the deep safety is caught in a dilemma between the two seam routes. Eli hit his outside receivers many times against the Falcons on these comeback routes, which proved very effective.

A lot of the Giants offense is comprised of quick passes, with three- and five-step drops from Manning. But when defenses key in on this tendency, New York is capable of catching them off guard:

The Giants run a lot of those aforementioned comeback routes along the sideline, but this one takes advantage of the defense's anticipation. The receiver subtly slows down like he's going to run the comeback, and the corner thinks he'll be able to jump the route. You can see the corner slow up for a second,waving his arms to keep balance through his change of direction. However, the receiver then keeps going, and this play would have been a touchdown if not for an overthrow by Manning. Still, a very effective play design. 

This next play is another kind of Cover 3 beater the Giants ran, but this call is especially brilliant because of the circumstances. 

On this 3rd and 4, the Falcons dropped into a more aggressive Cover 3 than usual because of the relatively short distance on this crucial down. The cornerbacks are playing closer to the line of scrimmage than normal, and the linebackers in coverage form a wall right along the first down line. However, the Giants send tight end Larry Donnell (84) on a crossing route right behind the linebackers, which the deep middle safety is forced to bite on because of the situation. With the middle of the field vacated, the left wide receiver has a clear area in which to run, and Manning finds him for a long gain. This is an excellent job by McAdoo predicting what the Falcons defense will do in third-and-medium in film study, and calling the perfect play to take advantage.

Here's another simple-yet-effective play design to get his receivers in space. The two receivers on the right side clear out that side of the field, allowing the left receiver to run across to the vacated space. Good job of realizing that Atlanta will be in man coverage.

The Giants like to run a lot of power running plays out of shotgun, and here's one that stuck out to me.

Usually you'll see the tight end cross the formation and kick out the defender containing the edge. However, on this play the left tackle blocks the edge defender while the tight end blocks the linebacker in the B gap. This is an interesting alteration, possibly made because the Giants' coaching staff doesn't trust tackle Will Beatty (65) to get to the second level and block the linebacker--instead, this play lures that linebacker into the tight end's block while Beatty doesn't have to do much. 

Obviously, a lot of what the Giants do is straight from Green Bay's playbook. They operate the extreme majority of the time out of 11 personnel--one running back, one tight end, and three wide receivers. Their offense is more horizontal than I initially expected--a lot of passes into the flat, screens, and quick slants and curls that get the ball out Manning's hands quickly--rather than vertical and downfield. The offensive line was pretty bad during the 2013 season, so this quick-hitting offense has helped the line out as well while masking one of the team's biggest weaknesses. 

New York's offense focuses on giving their receivers room to work, which fits perfectly with the Giants' athletic receiving corps. Victor Cruz is one of the most dangerous receivers in the NFL after the catch, and rookie wide receiver Odell Beckham Jr. looked very explosive and showed awesome body control in his first NFL action. 

None of this would work without Eli Manning. He seems to know right where to go with the ball, and if it isn't there, he'll check it down. His decision making last year was questionable to say the least, but this year he looks much more decisive and aware. 

But one of the biggest things that stuck out to me was McAdoo's playcalling and the apparent preparation of the offense as a whole. The Giants were prepared for everything Atlanta threw at them, and knew exactly when to audible due to Atlanta bringing extra pressure. The Giants also ran plays highlighted above that worked well against the cover 3 defense that the Falcons ran so often. 

McAdoo's offense looks fantastic so far. Not only are their staple plays effective, but the offense is diverse in that they can run a variety of plays off of their basic formations, which keeps the defense guessing. The Giants' biggest problem may soon be finding another offensive coordinator if and when a team deems McAdoo worthy enough for a head coaching position.