CJ Spiller is a bit of a question mark of a half back. Everyone knows that he's ridiculously talented, he has a great deal of speed, but he's never been a number one running back. He was always behind the seemingly ageless Fred Jackson in Buffalo, and his role in New Orleans shouldn't be much different. The biggest question surrounding Spiller is the same question that tends to plague players that the Saints sign out of Buffalo: Can he stay healthy?
However, this question is actually extremely overblown. At the very least, Spiller is willing to play through injury. Since being drafted in 2010, Spiller has played at least 14 games in every season except 2014, in which he played 9 games. If it happens again, it may dictate a trend, but for now Saints fans can sleep at night knowing that, as of now, it's an anomaly.
Spiller's role in Buffalo wasn't ever supposed to be a feature back. Below are Fred Jackson's stats vs Spiller's in the years that they played together.
As the table shows, one of the big problems that Buffalo faced in their backfield was having two hugely talented backs without an offense that let those backs get into space. It's actually impressive that they managed to get both backs 200 carries in 2013. And, on top of that, Spiller rushed for about 30 more yards on 6 less carries. He was an effective third down back, but in the two years that he got over 200 carries was when he played the best. This actually worries me, since the Saints are now taking Spiller and putting him in seemingly the same position by putting him behind Mark Ingram. The Saints signed Ingram to a solid extension this offseason, but they actually signed Spiller to a deal worth more money. Divvying up playing time between the two is going to be a very tricky proposition.
With all of this being said, it's worth taking a look at how Spiller performed when he was allowed into space by the Buffalo offense. Spiller's reception totals were fairly low throughout his Buffalo career (although he was clearly splitting a lot of his time), but his top end speed and ability to cut into space made him a very valuable asset in the passing game for the Bills when they used him, especially in situations in which defenses were keying in on the ridiculous speed that they had at the receiver position.
Buffalo comes onto the field in a traditional 11 formation, with Spiller lined up on the weak side. The receivers on this play's sole responsibility is to block downfield and create space for Spiller. Buffalo's line must make sure that no one gets outside of them before the ball does. Houston is in a nickel defense, with their extra corner over the slot receiver. Their staggered safeties actually work in Buffalo's favor, as the deeper one is weak side. This makes it easier to get to the Strong Safety off the line of scrimmage, allowing Spiller to get into a one on one situation.
This is exactly the same shot from two different angles. Houston is flowing to the ball effectively, but the corners are already committed to the receivers. Meanwhile, the Bills' linemen run a simple cut block (Saints fans should be familiar with the style) in order to not stop, but slow down the Houston pursuit to the outside (particularly JJ Watt). Once Spiller gets the ball outside, it's up to him to create in the space that he's given. The Houston formation was staggered strong side, which allows him to get into open space upon the reception. This was a one read play for quarterback EJ Manuel; no other player was intended to get the ball but Spiller on this play.
Once Spiller gets outside, the play is simply a footrace. Spiller is able to beat the defense out and get himself an easy first down on a 12 yard run. This kind of speed on the outside is why the Saints signed him, and it's why he'll fit in so effectively in the Sean Payton offense. It's a simple play that gets the speedster into space, and this is exactly the type of play that would fit well into Payton's third and short game.
Spiller also runs outside fairly well, in addition to being able to bounce it back inside if he sees a hole. In the same game against Houston, he shows an example of his elusiveness.
On this sweep play, Spiller starts to bounce the ball outside before realizing that his left tackle was being pushed too deep into the backfield. Spiller cuts it upfield and finds a secondary gap, while evading an ankle tackle in the process. He also forces multiple defenders to bring him down. Just looking at the way that the play was designed and broken down step by step shows how much thought goes into plays like this for a back.
One thing I'd like to note is that Buffalo is, again, in the 11 formation. This falls into the idea of Spiller as a type of 'scat' back, since it spreads the defense out. Houston is, once again, in the nickel (with the nickel back over the slot), but this time Spiller lines up strong side and sweeps weak. It's essentially an "iso" play of sorts for Spiller.
The easy decision, initially, looks to be to bounce the ball outside and find space in the open field. The line is holding their own, Sammy Watkins has the defender's attention, and Spiller can beat the defense outside. However, as the play progresses, this becomes a difficult prospect for Spiller.
Now it's decision time for Spiller, and his choices are above. When Watt (honestly, who else?) comes flying into the backfield, Spiller must change direction to evade him. Ironically, Watt redirects Spiller right into the hole that he needed to hit after Buffalo's tackle got pushed back into his path. If Spiller tries to bounce this further outside (or 'Barry Sanders' it, as the case may be), it would very likely turn into an intermediate loss. Spiller shoots through, and gets an easy 9 yards for the Bills.
Alas Spiller is, by no means, a perfect back. He can be susceptible to falling into the trap that so many backs that his speed fall into, that is to say, trying too hard to avoid any contact.
Spiller sees the gap closing, rather than closed, and tries to bounce the ball outside on this play. New England tracks him to the outside, and the ultimate result of the play is a three yard loss for Buffalo.
Buffalo lines up in a 12 set this time around, with the left side of the line (offense's left) stacked. They have one TE off the line. New England is in their Base 3-4 with 8 guys in the box, a single safety high and their corners right up on the Buffalo receivers (what I'm getting at here is that they know full well that it's a run).
Spiller instantly panics. Rather than cutting it upfield, he elects to try to go outside, where he's immediately met by three Patriots for a three yard loss. A laterally sound defense can effectively limit Spiller, which is why the Saints will need to mix up what they use him for: If they only bring him in for sweeps a la Darren Sproles in 2012/13, they're going to see quite a few negative plays out of Spiller.
Another note on the Buffalo offensive line is that in 2014 they were ranked 30th by Pro Football Focus. While they're by no means gospel, PFF is a fairly effective baseline for intangible play on the line and, also, in the secondary. They were also literally last in the league in run blocking. The Bills were 22nd in 2013, but also 29th in run blocking. Spiller rushed for 927 yards that year, as you can see above. They were more effective in 2012, coming in at 13th, but still 21st in the run game. This was Spiller's best year yardage wise, and his only 1,000 yard season. Finally, in 2011 Buffalo was 4th (12th in running) and 24th in 2010 (26th in running). With the exception of his rookie to second year, Spiller has been dealing with a steadily declining line, so a change of scenery could well be good for him.
One final way to use Spiller is to split him out, although no one needs to tell Sean Payton about that. The Bills only did so once in 2014, but they did it more in the earlier phases of Spiller's career. Spiller can fill the old Reggie Bush role in this regard. It's very likely that Payton sees the signing of Spiller as killing two birds with one stone, as he can move him around the formation and get a guy that can run between the tackles relatively effectively when Ingram needs a breather and Khiry Robinson is unavailable for whatever reason. Spiller didn't come cheap, so it seems silly to relegate to purely a third down back role. The Saints got him to spell Ingram, so expect to see him doing a lot of different things in the Sean Payton offense.