Heath Miller was undoubtedly an important part of Pittsburgh's offense. This season, he averaged 8.9 yards per reception. It's clear Ben Roethlisberger relied on him, and that any player is going to fill the giant shoes left behind will need somewhat similar productivity.
There are three other tight ends on the roster, Matt Spaeth, Jesse James and Xavier Grimble, but with a combination of age and inexperience at play with these players, it is unlikely that these three players alone will solve the problem at the tight end position. Therefore, the draft and free agency are where anyone wanting to solve this problem must look. Despite this, the current roster (especially Jesse James) still needs to be talked about.
I'm going to make this clear right now, I love Jesse James. He played in eight games this season, and averaged 7 yards per reception. That's not exactly the same as Miller's rookie season (11.8 yards per reception, and more importantly a Lombardi trophy to boot), but James has shown important development. James is going to be vital in the coming season to Pittsburgh.
The other tight ends, on the other hand, are a little less convincing. Xavier Grimble has never played a game in the NFL. His sheer lack of experience is an issue, and obviously, Grimble will not be the man to take Heath Miller's place on the line. Matt Spaeth is also less convincing than James. For a start, he's 32 years-old and has one year left on his current contract. He is one year younger than Miller, and has not had as big a role on the team compared to No. 83. Spaeth is not likely to be vital either.
The only player currently on the roster that is worth thinking about to fill Miller's role is Jesse James.
The NFL Draft is something that could help out here. Three tight ends come to mind: Austin Hooper (Stanford), Nick Vannett (Ohio State) and Bryce Williams (East Carolina). If Pittsburgh was to draft any of these players, they would have to go before round five.
Bryce Williams had 96 receptions for 1,045 yards(10.8 yards per reception) and 13 touchdowns on his career. He's tall (6'6") and is a great pass catcher. The only drawback is that he lacks mass and power. Nick Vannett on the other hand is a great run blocker, and over three seasons had an average of 11.75 yards per reception. Despite this, he was used more as a run blocker and actually only had 36 receptions. This lack of use by Ohio State's pass game means that he is unproven. Austin Hooper is the more complete package of the three. In two seasons he has had 74 receptions for 937 yards, that's an average of 12.6 yards. He's tall and broad, and although light at the moment, given time in an NFL weight room could put on another 20-pounds of muscle. He can line-block and catch. If the draft holds the solution, it is in one of these three players. Each has talent, each has strengths and each has weaknesses. Williams is not so great at the block; Vannett is not so great as a receiver, and Hooper needs to bulk up. Give any of them time in the NFL, in an offense as decisive as the Steelers, and any of them will be great in a season, but Pittsburgh has a whole to fill in the depth chart now, not in a season.
The only way to 100-percent solve the depth chart at tight end is with free agency. Some of that $4 million can be used here. Of course, the Steelers won't spend all of it on a single tight end, due to the need to secure other contracts already on the roster, but that doesn't mean that the Steelers won't look for a bargain veteran. Logan Paulsen (Washington Redskins) looks like a bargain. He's 28 years-old, and is worth $2.1 million. It's a shame that he only looks like a bargain. Paulsen didn't play a single game in 2015, and only had 12 starts in 2014 and averaged 6-yards per reception.
There are cheaper and more reliable alternatives available. Andrew Quarless (Green Bay Packers) and Coby Fleener (Indianapolis Colts) are the two players that Pittsburgh should be targeting. Both are 27 years-old. That means that are experienced but still have a number of years left. Both cost around $1.7 million, less than half the money that was freed up by Miller's retirement. Both had yards per reception comparable to Miller - Fleener with 9.1 yards per reception, Quarless with 7.8 yards per reception on the his 5 starts in 2015 but 11.1 yards per reception in 2014. Both players would fill the hole left by Miller, or at least until Jesse James is proven.
Obviously, Miller has left a huge hole in Pittsburgh's lineup. Jesse James shows promise, as does prospective draft players, but until these players can develop, there is still a lack of depth at tight end. The only way to ensure that this problem is solved would be to use free agency to acquire a veteran - ideally Fleener or Quarless - and in that time train up the remainder of the tight ends (James, and if Pittsburgh drafts a tight end hopefully Hooper, Vannett or Williams).
It is clear that Miller's shoes may never be filled, but by acquiring Fleener or Quarless, at least Pittsburgh's offense won't be without someone capable in the coming season.