I'm starting to wonder whether the manual penalty (the infamous 950 Penalty) uses the same algorithm as the sandbox for new sites, i.e. both have very low "Trust" ranking. A manual penalty is given to a site for against the policy and it's probably a manually set flag of being an "untrusted" site, while the sandbox effect is simply the lack of trust due to the age of the site.
Manual penalty is when a google editor notices you and thinks you've done something bad, but not bad enough to get you banned from Google completely. It does not affect your PageRank, but only the SERP, reducing the number of visitors from Google to something like 1/30 of the previous number or less.
My website is 3 years old and i was having good amount of traffic from the big "G". last week i had a sql injection attack on my website. Now i am nowhere in google, google has my page indexed and it is regularly visiting my website. So am I sandboxed??? or Penalised??? Not banned for sure as it indexed.