After Earl Thomas fractured his tibia versus the Carolina Panthers, many thought the Seahawks’ secondary would be fine with Steven Terrell as his replacement. Terrell, the undrafted safety out of Texas A&M University, has played for three different teams since entering the league in 2013: Starting with the Jacksonville Jaguars, he was picked up by the Houston Texas at the end of his rookie season, and then joined Seattle in July, 2014.

In Seattle’s defense, he typically plays as the deep free safety in their Cover 3 or Cover 1 packages. He occasionally buzzes into the underneath hook/curl zones similar to Kam Chancellor, and also plays man coverage on tight ends and running backs. Clearly, Pete Carroll and Kris Richard trust and expect him to play all the roles in their defense.

Take this touchdown pass versus the Green Bay Packers in the red zone. After Aaron Rodgers motions his running back outside, the secondary adjusts their coverage sending Terrell from zone to play man coverage on tight end (89) Jared Cook. Based on this shift, Rodgers thinks he has an opportunity to catch Terrell mid-adjustment.

After the snap, the safety does a good job of guarding the out-route forcing Rodgers to move onto another read. Rodgers then moves onto (87) Jordy Nelson’s crossing route for the score since (50) KJ Wright slipped in coverage. Even though the defense allowed the touchdown, Terrell showed fluid hips and an ability to stay with the athletic tight end.

Terrell has flashed potential in his limited snaps - more so in run defense - but he generally lacks the same level of instinctual play that Seattle fans have grown accustomed to with Earl Thomas as the deep safety in zone coverages.

A large part of this is his lack of understanding pursuit angles. There were multiple times in the loss to the Cardinals where Terrell was completely exposed. In the second quarter, the Seahawks run Cover 1 while blitzing KJ Wright.

Not only is Terrell late in reacting to the pass, but he completely takes out Jeremy Lane in the process with his poor pursuit angle.

This error allows the 80-yard score where if he took a more conservative angle, the two of them could have met to tackle Nelson for a 60-yard gain instead.

Later in the same game, Cardinals run a “packaged” play off of read-option. In this play design, Carson Palmer has the choice to hand the ball off to the running back or he can throw the slant to J.J. Nelson. Palmer decides to throw the slant.

Due to Terrell’s over-aggressive angle, Nelson slips past him for an additional 28 yards where they would score two plays later.

Another issue that plagues Terrell is that he is sometimes late reacting to running plays and late diagnosing fake handoffs as well.

Take for example when the Cardinals ran this power sweep in the middle of the fourth quarter. Running back (31) David Johnson takes five full steps before Terrell reacts out of his backpedal to drive towards the play.

Now realistically he would not have been able to make a play, but this is an example of something he needs to improve on to become a better safety.

Another example happened in Week 15 when the Rams ran a deep post-in combination versus the Seahawks Cover 3 defense. Terrell is caught watching Jared Goff execute his play-action fake. He is late reacting to (13) Mike Thomas burning past him. Luckily, Goff slightly underthrows his pass, while Thomas cold drops the ball anyways in typical Rams fashion.

It is not fair in my opinion to compare Terrell’s performance to the play of an All-Pro safety like Earl Thomas. Thomas has been exceptional since entering the NFL and has the best instincts of any active free safety in the game.

During Seattle’s tie versus Arizona earlier this season, Thomas was incredible showing the range and intelligence of a top safety. He stopped a deep touchdown pass to Michael Floyd by covering up for Richard Sherman’s error before helping DeShawn Shead to cover J.J. Nelson in the same play.

This type of play doesn’t receive the recognition it deserves by the media, but it certainly is noticed by the Seahawks coaching staff (and nerds like you and me who enjoy watching film).

Simply put, this defense is missing Earl Thomas more than it cares to admit. Thomas mentioned recently on Twitter that he’ll be returning to the team next season after considering retirement. Let’s hope he can make a full recovery or Seattle’s general manager John Schneider will have to make some changes over the offseason to help this secondary.

The Seahawks play the San Francisco 49ers to end their season. If they win and the Falcons lose, they will earn the two-seed and the bye week entering the playoffs. Seattle is currently favored by 10 points in Santa Clara and need to use this game to develop some consistency and momentum going forward.