Justin Smith has been on the right side of the defensive line since he arrived in 2008, and until recently, he hardly ever came off the field. Who takes over now that he's suddenly not there? The early plan is for Glenn Dorsey, who lined up in a similar spot when he was with the Chiefs, to take over on base downs and for Tank Carradine to come in on passing downs. That could mean a roughly 50-50 split for the season.
The dynamic between Carradine and linebacker Aldon Smith, who presumably would be playing next to him on passing downs, would be interesting. In his brief playing time last season, Carradine showed a knack for getting after the quarterback. He had three sacks in 146 snaps vs. Justin Smith's five sacks in 694 snaps.
Smith may not have had had Carradine's explosion and closing speed after 14 seasons, but he had plenty of strength, savvy and know-how when it came to the pass rush. And he worked very well with Aldon Smith, especially when it came to stunts in which Aldon Smith would duck to the inside of the line.
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Which is to say: Carradine may be a better pure pass rusher in Year 3 than Justin Smith was in Year 14, but Smith's presence led to an awful lot of sacks for the guy playing next to him.
A lot of fans and observers will see Smith's retirement as a blow against new coach Jim Tomsula. After all, Tomsula had been Smith's position coach ever since Smith arrived in San Francisco in 2008. That Tomsula couldn't lasso the Cowboy and reel him back from retirement reflects poorly on him, right?
Keep in mind, however, that Smith has been considering retirement for a while now. His offseason routine in recent years seemed to be to contemplate stepping away from the game only to eventually decide to give it one more season. My sense is that the spark that prompted Smith to return in previous seasons just wouldn't ignite this year.
At this point last year, every 49ers player and coach felt like they were on the cusp of a Super Bowl. After a ho-hum 8-8 season in 2014, and with all the offseason departures, it's hard to imagine there's anywhere close to the same expectation and excitement this year, which likely played a large role in dousing Smith's desire.
That, plus the fact that Smith realized his body never was going to improve from its current state -- indeed, it probably only would get worse -- seems to have prompted his decision more than anything else.
"You know when it’s time, you know?" Smith said Monday. "There’s a certain emotional, you know, you’ve got to go into things with the right mindset, this and that. It’s a young man’s game and you’ve got to be full of p--- and vinegar when you step onto the field. As you get older, it’s harder to get that same intensity going week in, week out and it’s just time to go."
Several reporters -- including me -- noted on Monday that Smith's retirement means that only three 49ers who started on defense in the Super Bowl just two and a half years ago remain with the team. They are Ahmad Brooks, NaVorro Bowman and Aldon Smith. Five members of the team's Super Bowl starting offense remain: Alex Boone, Anthony Davis, Vernon Davis, Colin Kaepernick and Joe Staley.
That seems like a massive sea change and underscores just how drastic the 49ers' offseason departures have been.
But are they really that abnormal?
Consider, for instance, the Ravens, the 49ers' opponents in the same Super Bowl. Only three members of their Super Bowl starting offense remain. Two players from the starting defense are still with the team.
You could have a very long conversation about Smith's best game as a 49er. Many will point to the win over the Eagles in 2011, which Smith sealed with a forced fumble and which sent a message that the 49ers, at best a mediocre squad in previous years that would always find a way to lose tight games, were now a contender.
Others will point to the Saints playoff game the same season (there was magic in 2011) in which Smith took down both quarterback Drew Brees and Brees' protector, Jermon Bushrod, with one arm. If you only had one play to show Smith's power, that would be the one you cued up.
For my money, however, the apex of Smith's career came the following week against the Giants. That game may have lacked the flash of 49ers-Saints, but it teemed with grit, intensity and trench warfare, which is where Smith excelled. It was an old-fashioned contest, power vs. power, a tank battle, a heavyweight bout from the 1950s.
Smith, Ray McDonald, Aldon Smith and Brooks tormented Eli Manning, muddied his jersey, forced turnovers and, if it were not for two botched punt returns, probably would have propelled the 49ers to the Super Bowl.
"Still stings," Smith said on Monday.