I think the pickup is similar to Benson Mayowa. Mayowa had two sacks in three seasons when we picked him up to be part of the rotation based on both potential and shown ability. He had six sacks that first year with us.
Basham is slightly more accomplished with 7.5 sacks in four seasons, but he's another young player who the team knows can play in this league but doesn't know how well. This has generally been Dallas' MO with defensive line signees. Last year, it tried to do things differently by signing washed-up vets, trying to squeeze another year out of them, and it backfired. So they returned to this formula.
Given what they are going to pay in FA, I'm OK with the move. Would I prefer to have a player at least averaging 5 or 6 sacks a season backing up our starters? Absolutely. Show me one we could have had as a backup for $2.5 million a season. I mean, we could have gotten Kerry Hyder for $3.4 million per year since he had 8.5 sacks for San Fran last year, but we did have Hyder the year before and he had one sack for us.
And maybe you can't imagine many teams with a top backup edge rusher averaging fewer sacks than Basham, but I just picked one at random (Washington, which had a much better defense than ours last year). According to the team's depth chart, its top backups at DE are James Smith-Williams, who had a half-sack as a rookie last year, and a foreign exchange player, David Bada, brought over this season. Beyond that, they have Jalen Jelks and rookies William Bradley-King and Shaka Toney.
I think if I continues to look at other teams' depth charts, I'd find that having DEs average 5 or 6 sacks per season backing up the starters is the exception, not the rule.