Thats a very tricky one mate. My best advice would be to use the in game filter 4 seasons in. For a defender i would say Tackling, Marking, Positioning, Anticipation, Jumpimg, Heading, Strength and Stamina try looking for players with 14 or more in these area's of course you prob wont find a player will all of these over 14 but worth a go.
As for a striker Finishing, Composure, Pace, Accelleration, I tend to thinki these are the major stats for a solid goalscoring striker to play the poacher or advanced forward role if you need a target man add Heading, jumping, Str and Stam.
By using the filter you might stumble across some very nice regens, I would love to give you some names but im blank at four seasons in. You could try and nab Fazio for the CB role and maybe someone like Machada or Delofonso from Aston Villa as your striker ohhhhh Pierre-Emerick Aubameyang can turn into a very good striker scores 20 a season on 10.2 at West Brom.